Managing non-volatile media

ABSTRACT

Apparatuses, systems, and methods are disclosed to manage non-volatile media. A method includes determining a configuration parameter for a set of storage cells of a non-volatile recording medium. A method includes reading data from a set of storage cells using a determined configuration parameter. A method includes adjusting a configuration parameter based on read data.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 14/106,566 entitled ‘MANAGING NON-VOLATILE” andfiled on Dec. 13, 2013 for John Strasser, et al., which is acontinuation of and claims priority to U.S. application Ser. No.13/719,045 entitled “MANAGING NON-VOLATILE MEDIA” and filed on Dec. 18,2012 for Robert Wood, et al., which is a continuation-in-part of andclaims priority to U.S. patent application Ser. No. 13/189,402 entitled“APPARATUS, SYSTEM, AND METHOD FOR DETERMINING A CONFIGURATION PARAMETERFOR SOLID-STATE STORAGE MEDIA” and filed on Jul. 22, 2011 for RobertWood, et al. which issued as U.S. Pat. No. 8,380,915, which claimspriority to U.S. patent application Ser. No. 13/015,458 entitled“APPARATUS, SYSTEM, AND METHOD FOR DETERMINING A READ VOLTAGE THRESHOLD”and filed on Jan. 27, 2011 for John Strasser, et al. which issued asU.S. Pat. No. 8,315,092 and U.S. patent application Ser. No. 13/175,637entitled “APPARATUS, SYSTEM, AND METHOD FOR USING MULTI-LEVEL CELLSTORAGE IN A SINGLE-LEVEL CELL MODE” and filed on Jul. 1, 2011 forRobert Wood, et al. which issued as U.S. Pat. No. 8,266,503, each ofwhich are incorporated herein by reference; U.S. patent application Ser.No. 13/015,458 claims priority to U.S. Provisional Patent ApplicationNo. 61/298,861 entitled “APPARATUS, SYSTEM, AND METHOD FOR DETERMINING AREAD VOLTAGE THRESHOLD FOR SOLID-STATE STORAGE MEDIA” and filed on Jan.27, 2010 for John Strasser, et al. and to U.S. Provisional PatentApplication No. 61/305,205 entitled “APPARATUS, SYSTEM, AND METHOD FORDETERMINING A READ VOLTAGE THRESHOLD FOR SOLID-STATE STORAGE MEDIA” andfiled on Feb. 17, 2010 for John Strasser, et al., each of which areincorporated herein by reference.

TECHNICAL FIELD

The subject matter disclosed herein relates to non-volatile media andmore particularly relates to configuration parameters for non-volatilemedia.

BACKGROUND

Many non-volatile storage devices distinguish between different binaryvalues that a storage cell may store based on a read voltage level ofthe storage cell, based on a resistivity of the storage cell, or basedon another configuration parameter of the storage cell. Non-volatilestorage devices may use one or more read voltage thresholds, resistivitythresholds, or the like to separate discrete values that may be storedin a storage cell.

Stored values, read voltage levels, resistivity, or the like, however,can shift over time. For example, storage cell damage, storage cellleakage, temperature, and other disturbances to storage cells can alterfor the state of storage cells, making different configurationparameters more optimal for the storage cells. The rate of leakage andother disturbances can also increase with age as storage cells are usedover time. If the read voltage level or other configuration parameter ofa storage cell shifts past a threshold for the storage cell, a dataerror occurs, as the value of the data read from the storage cell isdifferent than the value of the data written to the storage cell.

SUMMARY

A method is presented to manage non-volatile media. In one embodiment, amethod includes determining a configuration parameter for a set ofstorage cells of a solid state recording medium. A method, in a furtherembodiment, includes reading data from a set of storage cells using adetermined configuration parameter. In certain embodiments, a methodincludes adjusting a configuration parameter based on read data.

An apparatus is presented to manage non-volatile media. In oneembodiment, a configuration parameter module is configured to determinea read voltage threshold for one or more NAND flash storage cells. Astorage cell configuration module, in certain embodiments, is configuredto configure one or more storage cells to use a determined read voltagethreshold. In a further embodiment, an adjustment module is configuredto adjust a read voltage threshold based on closed loop feedback fromone or more NAND flash storage cells.

Another apparatus is presented to manage non-volatile media. In oneembodiment, an apparatus includes means for detecting an uncorrectableerror in data read from a set of non-volatile memory cells. Anapparatus, in a further embodiment, includes means for iterativelyadjusting one or more read voltage thresholds for a set of memory cellsand re-reading data from the set of memory cells until an uncorrectableerror in the data is correctable.

References throughout this specification to features, advantages, orsimilar language do not imply that all of the features and advantagesmay be realized in any single embodiment but are to be understood tomean that a specific feature, advantage, or characteristic is includedin at least one embodiment. The described features, advantages, andcharacteristics of the embodiments may be combined in any suitablemanner and may be practiced without one or more of the specific featuresor advantages of a particular embodiment. In other instances, additionalfeatures and advantages may be recognized in certain embodiments thatmay not be present in all embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the advantages of the disclosure will be readilyunderstood, a more particular description of the disclosure will berendered by reference to specific embodiments that are illustrated inthe appended drawings. Understanding that these drawings depict onlytypical embodiments and are not therefore to be considered to belimiting of its scope, the disclosure will be described and explainedwith additional specificity and detail through the use of theaccompanying drawings, in which:

FIG. 1 is a schematic block diagram illustrating one embodiment of asystem for managing a configuration parameter for non-volatile memorymedia;

FIG. 2 is a schematic block diagram illustrating one embodiment of anon-volatile memory device controller for non-volatile memory media;

FIG. 3A is a schematic block diagram illustrating one embodiment of anon-volatile memory controller with a write data pipeline and a readdata pipeline for non-volatile memory media;

FIG. 3B is a schematic block diagram illustrating another embodiment ofa non-volatile memory controller;

FIG. 4 is a schematic block diagram illustrating one embodiment of aconfiguration module;

FIG. 5 is a schematic block diagram illustrating one embodiment of aproactive configuration module;

FIG. 6A is a schematic block diagram illustrating one embodiment of anarray of storage elements of non-volatile memory media;

FIG. 6B is a schematic block diagram illustrating another embodiment ofan array of storage elements of non-volatile memory media;

FIG. 6C is a schematic block diagram illustrating one embodiment ofconfiguration parameters for a set of multi-level storage cells ofnon-volatile memory media;

FIG. 6D is a schematic block diagram illustrating one embodiment ofadjusted configuration parameters for a set of multi-level storage cellsof non-volatile memory media;

FIG. 6E is a graph illustrating one embodiment of a bit error rate andsets of pages;

FIG. 6F is a graph illustrating another embodiment of a bit error rateand sets of pages;

FIG. 6G is a graph illustrating a further embodiment of a bit error rateand sets of pages;

FIG. 7A is a schematic block diagram illustrating one embodiment of amedia characteristic module and a media characteristic repository;

FIG. 7B is a schematic block diagram illustrating one embodiment of amedia characteristic repository;

FIG. 8A is a schematic block diagram illustrating one embodiment of aconfiguration parameter module and a configuration parameter repository;

FIG. 8B is a schematic block diagram illustrating one embodiment of aconfiguration parameter repository;

FIG. 9 is a schematic flow chart diagram illustrating one embodiment ofa method for managing non-volatile media; and

FIG. 10 is a schematic flow chart diagram illustrating anotherembodiment of a method for managing non-volatile media.

DETAILED DESCRIPTION

Many of the functional units described in this specification have beenlabeled as modules, in order to more particularly emphasize theirimplementation independence. For example, a module may be implemented asa hardware circuit comprising custom VLSI circuits or gate arrays,off-the-shelf semiconductors such as logic chips, transistors, or otherdiscrete components. A module may also be implemented in programmablehardware devices such as field programmable gate arrays, programmablearray logic, programmable logic devices or the like.

Modules may also be implemented in software for execution by varioustypes of processors. An identified module of executable code may, forinstance, comprise one or more physical or logical blocks of computerinstructions which may, for instance, be organized as an object,procedure, or function. Nevertheless, the executables of an identifiedmodule need not be physically located together, but may comprisedisparate instructions stored in different locations which, when joinedlogically together, comprise the module and achieve the stated purposefor the module.

Indeed, a module of executable code may be a single instruction, or manyinstructions, and may even be distributed over several different codesegments, among different programs, and across several memory devices.Similarly, operational data may be identified and illustrated hereinwithin modules, and may be embodied in any suitable form and organizedwithin any suitable type of data structure. The operational data may becollected as a single data set, or may be distributed over differentlocations including over different storage devices, and may exist, atleast partially, merely as electronic signals on a system or network.Where a module or portions of a module are implemented in software, thesoftware portions are stored on one or more computer readable media.

Reference throughout this specification to “one embodiment,” “anembodiment,” or similar language means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the present disclosure. Thus,appearances of the phrases “in one embodiment,” “in an embodiment,” andsimilar language throughout this specification may, but do notnecessarily, all refer to the same embodiment.

Reference to a computer readable medium may take any form capable ofstoring machine-readable instructions on a digital processing apparatusmemory device. A computer readable medium may be embodied by a compactdisk, digital-video disk, a magnetic tape, a Bernoulli drive, a magneticdisk, a punch card, flash memory, integrated circuits, or other digitalprocessing apparatus memory device.

Furthermore, the described features, structures, or characteristics ofthe disclosure may be combined in any suitable manner in one or moreembodiments. In the following description, numerous specific details areprovided, such as examples of programming, software modules, userselections, network transactions, database queries, database structures,hardware modules, hardware circuits, hardware chips, etc., to provide athorough understanding of embodiments of the disclosure. One skilled inthe relevant art will recognize, however, that the disclosure may bepracticed without one or more of the specific details, or with othermethods, components, materials, and so forth. In other instances,well-known structures, materials, or operations are not shown ordescribed in detail to avoid obscuring aspects of the disclosure.

The schematic flow chart diagrams included herein are generally setforth as logical flow chart diagrams. As such, the depicted order andlabeled steps are indicative of one embodiment of the presented method.Other steps and methods may be conceived that are equivalent infunction, logic, or effect to one or more steps, or portions thereof, ofthe illustrated method. Additionally, the format and symbols employedare provided to explain the logical steps of the method and areunderstood not to limit the scope of the method. Although various arrowtypes and line types may be employed in the flow chart diagrams, theyare understood not to limit the scope of the corresponding method.Indeed, some arrows or other connectors may be used to indicate only thelogical flow of the method. For instance, an arrow may indicate awaiting or monitoring period of unspecified duration between enumeratedsteps of the depicted method. Additionally, the order in which aparticular method occurs may or may not strictly adhere to the order ofthe corresponding steps shown.

Non-Volatile Memory System

FIG. 1 depicts one embodiment of a system 100 for managing non-volatilememory media 110. The system 100 includes a non-volatile memory device102, a non-volatile memory controller 104, a write data pipeline 106, aread data pipeline 108, non-volatile memory media 110, a computer 112, aclient 114, and a computer network 116, which are described below.

The system 100 includes at least one non-volatile memory device 102. Inother embodiments, the system 100 includes two or more non-volatilememory devices 102. Each non-volatile memory device 102 may includenon-volatile memory media 110. The non-volatile memory media may includesolid-state storage media such as NAND flash memory, NOR flash memory,nano random access memory (“nano RAM or NRAM”), magneto-resistive RAM(“MRAM”), dynamic RAM (“DRAM”), phase change RAM (“PRAM”), racetrackmemory, memristor memory, nanocrystal wire-based memory, silicon-oxidebased sub-10 nanometer process memory, graphene memory,silicon-oxide-nitride-oxide-silicon (“SONOS”) memory, resistiverandom-access memory (“RRAM”), programmable metallization cell (“PMC”),conductive-bridging RAM (“CBRAM”), or the like. In other embodiments,the non-volatile memory media 110 may comprise magnetic media, opticalmedia, or another type of non-volatile media.

While the non-volatile memory media 110 is referred to herein as “memorymedia,” in various embodiments, the non-volatile memory media 110 maymore generally comprise a non-volatile recording media capable ofrecording data, which may be referred to as a non-volatile memory media,a non-volatile storage media, or the like. Further, the non-volatilememory device 102, in various embodiments, may comprise or be referredto as a non-volatile recording device, a non-volatile memory device, anon-volatile storage device, or the like. The non-volatile memory device102 is described in more detail with respect to FIGS. 2, 3A, and 3B.

The non-volatile memory device 102 is depicted in a computer 112connected to one or more clients 114 through a computer network 116. Inone embodiment, the non-volatile memory device 102 is internal to thecomputer 112 and is connected using a system communications bus, such asa peripheral component interconnect express (“PCI-e”) bus, a SerialAdvanced Technology Attachment (“serial ATA”) bus, or the like. Inanother embodiment, the non-volatile memory device 102 is external tothe computer 112 and is connected using an external communications bus,such as a universal serial bus (“USB”) connection, an Institute ofElectrical and Electronics Engineers (“IEEE”) 1394 bus (“FireWire”), orthe like. In other embodiments, the non-volatile memory device 102 isconnected to the computer 112 using a communications bus such as aperipheral component interconnect (“PCI”) express bus using externalelectrical or optical bus extension or bus networking solution such asInfiniband or PCI Express Advanced Switching (“PCIe-AS”), or the like.

In various embodiments, the non-volatile memory device 102 may be in theform of a dual-inline memory module (“DIMM”), a daughter card, or amicro-module. In another embodiment, the non-volatile memory device 102is an element within a rack-mounted blade. In another embodiment, thenon-volatile memory device 102 is contained within a package that isintegrated directly onto a higher level assembly (e.g., mother board,lap top, graphics processor). In another embodiment, individualcomponents comprising the non-volatile memory device 102 are integrateddirectly onto a higher level assembly without intermediate packaging.

The non-volatile memory device 102 includes one or more non-volatilememory controllers 104, each may include a write data pipeline 106 and aread data pipeline 108, and each includes non-volatile memory media 110,which are described in more detail below with respect to FIGS. 2, 3A,and 3B. In general, the one or more non-volatile memory controllers 104manage the non-volatile memory media 110, including determiningconfiguration parameters for storage cells of the non-volatile memorymedia 110 and configuring the storage cells according to theconfiguration parameters.

As used herein, a configuration parameter for a set of storage cells orother non-volatile memory media 110 is a parameter that is modifiable byway of an interface. The interface may comprise a publicly knowninterface or a proprietary interface and may include use of particularcommand instructions and/or use of particular parameters, registersettings, driver settings, controller settings, a particular set ofcommand instruction sequences, or other differences from regularcommands (general purpose commands) or settings used to interface withor manage the set of storage cells. Configuration parameters may relateto writing to, or programming, storage cells, reading from storagecells, erasing storage cells, managing storage cells, device driver orstorage controller settings for storage cells, or the like. Aconfiguration parameter for a set of storage cells may be associatedwith a device driver for the non-volatile memory device 102, with anon-volatile memory controller 104, or the like, and may relate to howthe device driver and/or non-volatile memory controller 104 use, manage,and interact with the set of storage cells and/or the non-volatilememory media 110.

A configuration parameter, in certain embodiments, may include one ormore storage thresholds, such as a read voltage threshold, a resistivitythreshold, a programming threshold, an erase threshold, a hardwaredriver level threshold, a storage controller level threshold, or thelike. The configuration parameter may be set once during initializationof the non-volatile memory media 110, dynamically with each commandissued to the non-volatile memory media 110, or during operation of thenon-volatile memory media 110 in response to triggers such as events ortime intervals. The non-volatile memory controller 104, in oneembodiment, proactively sets one or more configuration parameters forstorage cells of the non-volatile memory media 110 to improve theutility of the non-volatile memory media 110, to reduce errors, and thelike.

The system 100 includes one or more computers 112 connected to thenon-volatile memory device 102. A computer 112 may be a host, a server,a storage controller of a storage area network (“SAN”), a workstation, apersonal computer, a laptop computer, a handheld computer, asupercomputer, a computer cluster, a network switch, a router orappliance, a database or storage appliance, a data acquisition or datacapture system, a diagnostic system, a test system, a robot, a portableelectronic device, a wireless device, or the like. In anotherembodiment, a computer 112 may be a client and the non-volatile memorydevice 102 operates autonomously to service data requests sent from thecomputer 112. In this embodiment, the computer 112 and non-volatilememory device 102 may be connected using a computer network, system bus,or other communication means suitable for connection between a computer112 and an autonomous non-volatile memory device 102.

In one embodiment, the system 100 includes one or more clients 114connected to one or more computers 112 through one or more computernetworks 116. A client 114 may be a host, a server, a storage controllerof a SAN, a workstation, a personal computer, a laptop computer, ahandheld computer, a supercomputer, a computer cluster, a networkswitch, a router or appliance, a database or storage appliance, a dataacquisition or data capture system, a diagnostic system, a test system,a robot, a portable electronic device, a wireless device, or the like.The computer network 116 may include the Internet, a wide area network(“WAN”), a metropolitan area network (“MAN”), a local area network(“LAN”), a token ring, a wireless network, a fiber channel network, aSAN, network attached storage (“NAS”), ESCON, or the like, or anycombination of networks. The computer network 116 may also include anetwork from the IEEE 802 family of network technologies, such asEthernet, token ring, WiFi, WiMax, and the like.

The computer network 116 may include servers, switches, routers,cabling, radios, and other equipment used to facilitate networkingcomputers 112 and clients 114. In one embodiment, the system 100includes multiple computers 112 that communicate as peers over acomputer network 116. In another embodiment, the system 100 includesmultiple non-volatile memory devices 102 that communicate as peers overa computer network 116. One of skill in the art will recognize othercomputer networks 116 comprising one or more computer networks 116 andrelated equipment with single or redundant connection between one ormore clients 114 or other computer with one or more non-volatile memorydevices 102 or one or more non-volatile memory devices 102 connected toone or more computers 112. In one embodiment, the system 100 includestwo or more non-volatile memory devices 102 connected through thecomputer network 116 to a client 114 without a computer 112. Thenon-volatile memory controller 104, in certain embodiments, receivessource data for storage in the non-volatile memory media 110 from aprocessor of the computer 112 and/or from a client 114 over one or morecommunications buses as described above.

Non-Volatile Memory Device

FIG. 2 depicts one embodiment 200 of a non-volatile memory devicecontroller 202 that includes a write data pipeline 106 and a read datapipeline 108 in a non-volatile memory device 102. The non-volatilememory device controller 202 may be embodied as hardware, as software,or as a combination of hardware and software. The non-volatile memorydevice controller 202 may include a number of non-volatile memorycontrollers 0-N 104 a-n, each controlling non-volatile memory media 110.In the depicted embodiment, two non-volatile memory controllers areshown: non-volatile memory controller 0 104 a and non-volatile memorycontroller N 104 n, and each controls non-volatile memory media 110 a-n.In the depicted embodiment, non-volatile memory controller 0 104 acontrols a data channel so that the attached non-volatile memory media110 a stores data. Non-volatile memory controller N 104 n controls anindex metadata channel associated with the stored data and theassociated non-volatile memory media 110 n stores index metadata.

In an alternate embodiment, the non-volatile memory device controller202 includes a single non-volatile memory controller 104 a with a singlenon-volatile memory media 110 a. In another embodiment, there are aplurality of non-volatile memory controllers 104 a-n and associatednon-volatile memory media 110 a-n. In one embodiment, one or morenon-volatile memory controllers 104 a-104 n-l, coupled to theirassociated non-volatile memory media 110 a-110 n-l, control data whileat least one non-volatile memory controller 104 n, coupled to itsassociated non-volatile memory media 110 n, controls index metadata.

In one embodiment, at least one non-volatile memory controller 104includes a field-programmable gate array (“FPGA”) and controllerfunctions are programmed into the FPGA. In a particular embodiment, theFPGA is a Xilinx® FPGA. In another embodiment, the non-volatile memorycontroller 104 comprises components specifically designed as anon-volatile memory controller 104, such as an application-specificintegrated circuit (“ASIC”) or custom logic solution. Each non-volatilememory controller 104 typically includes a write data pipeline 106 and aread data pipeline 108, which are describe further in relation to FIG.3A. In another embodiment, at least one non-volatile memory controller104 is made up of a combination FPGA, ASIC, and custom logic components.In certain embodiments, at least a portion of a non-volatile memorycontroller 104 is integrated with, part of, and/or in communication witha device driver executing on the computer 112, or the like.

Non-Volatile Memory

The non-volatile memory media 110 is an array of non-volatile memoryelements 216, 218, 220, arranged in banks 214, and accessed in parallelthrough a bi-directional storage input/output (“I/O”) bus 210. Thestorage I/O bus 210, in one embodiment, is capable of unidirectionalcommunication at any one time. For example, when data is being writtento the non-volatile memory media 110, data cannot be read from thenon-volatile memory media 110. In another embodiment, data can flow bothdirections simultaneously. However bi-directional, as used herein withrespect to a data bus, refers to a data pathway that can have dataflowing in only one direction at a time, but when data flowing onedirection on the bi-directional data bus is stopped, data can flow inthe opposite direction on the bi-directional data bus.

A non-volatile memory element (e.g., NVM 0.0 216 a) is typicallyconfigured as a chip (a package of one or more die) or a die on acircuit board. As depicted, a non-volatile memory element (e.g., 216 a)operates independently or semi-independently of other non-volatilememory elements (e.g., 218 a) even if these several elements arepackaged together in a chip package, a stack of chip packages, or someother package element. As depicted, a row of non-volatile memoryelements 216 a, 216 b, 216 m is designated as a bank 214. As depicted,there may be “n” banks 214 a-n and “m” non-volatile memory elements 216a-m, 218 a-m, 220 a-m per bank in an array of n×m non-volatile memoryelements 216, 218, 220 in a non-volatile memory media 110. Of coursedifferent embodiments may include different values for n and m.

In one embodiment, the non-volatile memory media 110 a includes twentynon-volatile memory elements 216, 218, 220 per bank 214 with eight banks214. In one embodiment, the non-volatile memory media 110 a includestwenty four non-volatile memory elements 216, 218, 220 per bank 214 witheight banks 214. In addition to the n×m storage elements 216, 218, 220,one or more additional columns (P) may also be addressed and operated inparallel with other non-volatile memory elements 216 a, 216 b, 216 m forone or more rows. The added P columns in one embodiment, store paritydata for the portions of an ECC chunk (e.g., an ECC codeword) that spanm storage elements for a particular bank. In one embodiment, eachnon-volatile memory element 216, 218, 220 is comprised of single-levelcell (“SLC”) devices. In another embodiment, each non-volatile memoryelement 216, 218, 220 is comprised of multi-level cell (“MLC”) devices.

In one embodiment, non-volatile memory elements that share a commonstorage I/O bus 210 a-210 n (e.g., 216 b, 218 b, 220 b) are packagedtogether. In one embodiment, a non-volatile memory element 216, 218, 220may have one or more die per chip with one or more chips stackedvertically and each die may be accessed independently. In anotherembodiment, a non-volatile memory element (e.g., NVM 0.0 216 a) may haveone or more virtual die per die and one or more die per chip and one ormore chips stacked vertically and each virtual die may be accessedindependently. In another embodiment, a non-volatile memory element NVM0.0 216 a may have one or more virtual die per die and one or more dieper chip with some or all of the one or more die stacked vertically andeach virtual die may be accessed independently.

In one embodiment, two die are stacked vertically with four stacks pergroup to form eight storage elements (e.g., NVM 0.0-NVM 8.0) 216 a-220a, each in a separate bank 214 a-n. In another embodiment, 24 storageelements (e.g., NVM 0.0-NVM 0.24) 216 form a logical bank 214 a so thateach of the eight logical banks has 24 storage elements (e.g.,NVM0.0-NVM 8.24) 216, 218, 220. Data is sent to the non-volatile memorymedia 110 over the storage I/O bus 210 to all storage elements of aparticular group of storage elements (NVM 0.0-NVM 8.0) 216 a, 218 a, 220a. The one or more storage control buses 212 a-212 n are used to selecta particular bank (e.g., Bank 0 214 a) so that the data received overthe storage I/O bus 210 connected to all banks 214 is written just tothe selected bank 214 a.

In certain embodiments, the storage control bus 212 and storage I/O bus210 are used together by the non-volatile memory controller 104 tocommunicate addressing information, storage element command information,and data to be stored. Those of skill in the art recognize that thisaddress, data, and command information may be communicated using one orthe other of these buses 212, 210, or using separate buses for each typeof control information. In one embodiment, addressing information,storage element command information, and storage data travel on thestorage I/O bus 210 and the storage control bus 212 carries signals foractivating a bank as well as identifying whether the data on the storageI/O bus 210 lines constitute addressing information, storage elementcommand information, or storage data.

For example, a control signal on the storage control bus 212 such as“command enable” may indicate that the data on the storage I/O bus 210lines is a storage element command such as program, erase, reset, read,and the like. A control signal on the storage control bus 212 such as“address enable” may indicate that the data on the storage I/O bus 210lines is addressing information such as erase block identifier, pageidentifier, and optionally offset within the page within a particularstorage element. Finally, an absence of a control signal on the storagecontrol bus 212 for both “command enable” and “address enable” mayindicate that the data on the storage I/O bus 210 lines is storage datathat is to be stored on the storage element at a previously addressederase block, physical page, and optionally offset within the page of aparticular storage element.

In one embodiment, the storage I/O bus 210 is comprised of one or moreindependent I/O buses (“IIOBa-m” comprising 210 a.a-m, 210 n.a-m)wherein the non-volatile memory elements within each column share one ofthe independent I/O buses that accesses each non-volatile memory element216, 218, 220 in parallel so that all banks 214 are accessedsimultaneously. For example, one channel of the storage I/O bus 210 mayaccess a first non-volatile memory element 216 a, 218 a, 220 a of eachbank 214 a-n simultaneously. A second channel of the storage I/O bus 210may access a second non-volatile memory element 216 b, 218 b, 220 b ofeach bank 214 a-n simultaneously. Each row of non-volatile memoryelement 216 a, 216 b, 216 m is accessed simultaneously.

In one embodiment, where non-volatile memory elements 216, 218, 220 aremulti-level (physically stacked), all physical levels of thenon-volatile memory elements 216, 218, 220 are accessed simultaneously.As used herein, “simultaneously” also includes near simultaneous accesswhere devices are accessed at slightly different intervals to avoidswitching noise. Simultaneously is used in this context to bedistinguished from a sequential or serial access wherein commands and/ordata are sent individually one after the other.

Typically, banks 214 a-n are independently selected using the storagecontrol bus 212. In one embodiment, a bank 214 is selected using a chipenable or chip select. Where both chip select and chip enable areavailable, the storage control bus 212 may select one level of amulti-level non-volatile memory element 216, 218, 220. In otherembodiments, other commands are used by the storage control bus 212 toindividually select one level of a multi-level non-volatile memoryelement 216, 218, 220. Non-volatile memory elements 216, 218, 220 mayalso be selected through a combination of control and of addressinformation transmitted on storage I/O bus 210 and the storage controlbus 212.

In one embodiment, each non-volatile memory element 216, 218, 220 ispartitioned into erase blocks and each erase block is partitioned intopages. An erase block on a non-volatile memory element 216, 218 220 maybe called a physical erase block or “PEB.” A typical page is 2000 bytes(“2 kB”). In one example, a non-volatile memory element (e.g., NVM 0.0)includes two registers and can program two pages so that a two-registernon-volatile memory element 216, 218, 220 has a capacity of 4 kB. A bank214 of 20 non-volatile memory elements 216 a, 216 b, 216 m would thenhave an 80 kB capacity of pages accessed with the same address going outthe channels of the storage I/O bus 210.

This group of pages in a bank 214 of non-volatile memory elements 216 a,216 b, 216 m of 80 kB may be called a logical page or virtual page.Similarly, a physical erase block of each storage element 216 a-m of abank 214 a may be grouped to form a logical erase block (“LEB”) or avirtual erase block. An LEB, in certain embodiments, is sized to fitwithin a bank 214 a-m, with one PEB from each storage element 216 a-m ofa bank 214 a forming an LEB, or the like. In other embodiments, an LEBmay span banks 214 a-n, and may comprise one or more PEBs 608 a-m frommultiple banks 602 a-m. In one embodiment, an erase block (logical orphysical) of pages within a non-volatile memory element 216, 218, 220 iserased when an erase command is received within a non-volatile memoryelement 216, 218, 220. Whereas the size and number of erase blocks,pages, planes, or other logical and physical divisions within anon-volatile memory element 216, 218, 220 are expected to change overtime with advancements in technology, it is to be expected that manyembodiments consistent with new configurations are possible and areconsistent with the general description herein.

Typically, when a packet is written to a particular location within anon-volatile memory element 216, 218, 220, wherein the packet isintended to be written to a location within a particular page which isspecific to a particular physical erase block of a particular storageelement of a particular bank, a physical address is sent on the storageI/O bus 210 and followed by the packet. The physical address containsenough information for the non-volatile memory element 216, 218, 220 todirect the packet to the designated location within the page. Since allstorage elements in a column of storage elements (e.g., NVM 0.0-NVM N.0216 a, 218 a, 220 a) are accessed simultaneously by the appropriate buswithin the storage I/O bus 210 a.a, to reach the proper page and toavoid writing the data packet to similarly addressed pages in the columnof storage elements (NVM 0.0-NVM N.0 216 a, 218 a, 220 a), the bank 214a that includes the non-volatile memory element NVM 0.0 216 a with thecorrect page where the data packet is to be written is simultaneouslyselected by the storage control bus 212.

Similarly, satisfying a read command on the storage I/O bus 210 mayrequire a substantially simultaneous signal on the storage control bus212 to select a single bank 214 a and the appropriate page within thatbank 214 a. In one embodiment, a read command reads an entire page, andbecause there are multiple non-volatile memory elements 216 a, 216 b,216 m in parallel in a bank 214, an entire logical page is read with aread command. However, the read command may be broken into subcommands,as will be explained below with respect to bank interleave. A logicalpage may also be accessed in a write operation.

An erase block erase command may be sent out to erase an erase blockover the storage I/O bus 210 with a particular erase block address toerase a particular erase block. Typically, an erase block erase commandmay be sent over the parallel paths of the storage I/O bus 210 to erasea logical erase block, each with a particular erase block address toerase a particular erase block. Simultaneously a particular bank (e.g.,Bank 0 214 a) is selected over the storage control bus 212 to preventerasure of similarly addressed erase blocks in all of the banks (Banks1-N 214 b-n). Alternatively, no particular bank (e.g., Bank 0 214 a) isselected over the storage control bus 212 to enable erasure of similarlyaddressed erase blocks in all of the banks (Banks 1-N 214 b-n)simultaneously. Other commands may also be sent to a particular locationusing a combination of the storage I/O bus 210 and the storage controlbus 212. One of skill in the art will recognize other ways to select aparticular storage location using the bi-directional storage I/O bus 210and the storage control bus 212.

In one embodiment, packets are written sequentially to the non-volatilememory media 110. For example, packets are streamed to the storage writebuffers of a bank 214 a of storage elements 216 and when the buffers arefull, the packets are programmed to a designated logical page. Packetsthen refill the storage write buffers and, when full, the packets arewritten to the next logical page. The next logical page may be in thesame bank 214 a or another bank (e.g., 214 b). This process continues,logical page after logical page, typically until a logical erase block(“LEB”) is filled. In another embodiment, the streaming may continueacross logical erase block boundaries with the process continuing,logical erase block after logical erase block.

In a read, modify, write operation, data packets associated withrequested data are located and read in a read operation. Data segmentsof the modified requested data that have been modified are not writtento the location from which they are read. Instead, the modified datasegments are again converted to data packets and then writtensequentially to the next available location in the logical pagecurrently being written. The index entries for the respective datapackets are modified to point to the packets that contain the modifieddata segments. The entry or entries in the index for data packetsassociated with the same requested data that have not been modified willinclude pointers to original location of the unmodified data packets.Thus, if the original requested data is maintained, for example tomaintain a previous version of the requested data, the originalrequested data will have pointers in the index to all data packets asoriginally written. The new requested data will have pointers in theindex to some of the original data packets and pointers to the modifieddata packets in the logical page that is currently being written.

In a copy operation, the index includes an entry for the originalrequested data mapped to a number of packets stored in the non-volatilememory media 110. When a copy is made, a new copy of the requested datais created and a new entry is created in the index mapping the new copyof the requested data to the original packets. The new copy of therequested data is also written to the non-volatile memory media 110 withits location mapped to the new entry in the index. The new copy of therequested data packets may be used to identify the packets within theoriginal requested data that are referenced in case changes have beenmade in the original requested data that have not been propagated to thecopy of the requested data and the index is lost or corrupted.

Beneficially, sequentially writing packets facilitates a more even useof the non-volatile memory media 110 and allows the non-volatile memorydevice controller 202 to monitor storage hot spots and level usage ofthe various logical pages in the non-volatile memory media 110.Sequentially writing packets also facilitates a powerful, efficientgarbage collection system, which is described in detail below. One ofskill in the art will recognize other benefits of sequential storage ofdata packets.

In various embodiments, the non-volatile memory device controller 202also includes a data bus 204, a local bus 206, a buffer controller 208,buffers 0-N 222 a-n, a master controller 224, a direct memory access(“DMA”) controller 226, a memory controller 228, a dynamic memory array230, a static random memory array 232, a management controller 234, amanagement bus 236, a bridge 238 to a system bus 240, and miscellaneouslogic 242. In other embodiments, the system bus 240 is coupled to one ormore network interface cards (“NICs”) 244, some of which may includeremote DMA (“RDMA”) controllers 246, one or more central processing unit(“CPU”) 248, one or more external memory controllers 250 and associatedexternal memory arrays 252, one or more storage controllers 254, peercontrollers 256, and application specific processors 258. The components244-258 connected to the system bus 240 may be located in the computer112 or may be other devices.

Data Pipelines

FIG. 3A depicts one embodiment 300 of a non-volatile memory controller104 with a write data pipeline 106 and a read data pipeline 108 in anon-volatile memory device 102. The embodiment 300 includes a data bus204, a local bus 206, and buffer control 208, which are substantiallysimilar to those described in relation to the non-volatile memory devicecontroller 202 of FIG. 2. The write data pipeline 106 includes apacketizer 302 and an error-correcting code (“ECC”) encoder 304. Inother embodiments, the write data pipeline 106 includes an input buffer306, a write synchronization buffer 308, a write program module 310, acompression module 312, an encryption module 314, a garbage collectorbypass 316 (with a portion within the read data pipeline 108), a biasmodule 318, and a write buffer 320. The read data pipeline 108 includesa read synchronization buffer 328, an ECC decoder 322, a depacketizer324, an alignment module 326, and an output buffer 330. In otherembodiments, the read data pipeline 108 may include an inverse biasmodule 332, a portion of the garbage collector bypass 316, a decryptionmodule 334, a decompression module 336, and a read program module 338.

The non-volatile memory controller 104 may also include control andstatus registers 340 and control queues 342, a bank interleavecontroller 344, a synchronization buffer 346, a storage bus controller348, and a multiplexer (“MUX”) 350. The non-volatile memory controller104, in the depicted embodiment, includes a configuration module 352that may be part of the write data pipeline 106 and/or part of the readdata pipeline 108, or may be independent from the write data pipeline106 and the read data pipeline 108. The components of the non-volatilememory controller 104 and associated write data pipeline 106 and readdata pipeline 108 are described below. In other embodiments, synchronousnon-volatile memory media 110 may be used and synchronization buffers308, 328 may be eliminated.

The write data pipeline 106 includes an ECC encoder 304 that thatgenerates one or more error-correcting codes (“ECC”) for the one or morepackets received from the packetizer 302. The ECC encoder 304 typicallyuses an error correcting algorithm to generate ECC check bits which arestored with the one or more data packets. The ECC codes generated by theECC encoder 304 together with the one or more data packets associatedwith the ECC codes comprise an ECC chunk/codeword. The ECC data storedwith the one or more data packets is used to detect and to correcterrors introduced into the data through transmission and storage. In oneembodiment, packets are streamed into the ECC encoder 304 as un-encodedblocks of length N. A syndrome of length S is calculated, appended andoutput as an encoded block of length N+S. The value of N and S aredependent upon the characteristics of the algorithm which is selected toachieve specific performance, efficiency, and robustness metrics. In oneembodiment, there is no fixed relationship between the ECC blocks andthe packets; the packet may comprise more than one ECC block; the ECCblock may comprise more than one packet; and a first packet may endanywhere within the ECC block and a second packet may begin after theend of the first packet within the same ECC block. In one embodiment,ECC algorithms are not dynamically modified. In one embodiment, the ECCdata stored with the data packets is robust enough to correct errors inmore than two bits.

Beneficially, using a robust ECC algorithm allowing more than single bitcorrection or even double bit correction allows the life of thenon-volatile memory media 110 to be extended. For example, if flashmemory is used as the storage medium in the non-volatile memory media110, the flash memory may be written approximately 100,000 times withouterror per erase cycle. This usage limit may be extended using a robustECC algorithm. Having the ECC encoder 304 and corresponding ECC decoder322 onboard the non-volatile memory device 102, the non-volatile memorydevice 102 can internally correct errors and has a longer useful lifethan if a less robust ECC algorithm is used, such as single bitcorrection. However, in other embodiments the ECC encoder 304 may use aless robust algorithm and may correct single-bit or double-bit errors.In another embodiment, the non-volatile memory media 110 may compriseless reliable storage such as multi-level cell (“MLC”) flash in order toincrease capacity, which storage may not be sufficiently reliablewithout more robust ECC algorithms.

In one embodiment, the write data pipeline 106 also includes a biasmodule 318 that receives the one or more packets from the packetizer302, either directly or indirectly. The bias module 318 biases the bitsof the data packets toward a bias of storage cells of the non-volatilememory media 110. As used herein, a “bias” is a preference, probability,tendency, or desirability of values for bits within a set of bits toexhibit a specific data pattern. A bias may be a natural property, adesigned attribute, a property of performing an operation onnon-volatile memory media, or a random occurrence. Data itself may havea bias and non-volatile memory media may have a bias. A bias may betoward binary ones, toward binary zeroes, toward a balance of binaryones and zeroes, toward a certain binary value for certain bits, or thelike.

For example, in one embodiment, end sections of data files may be paddedwith binary zeroes, causing the data packets that store the end sectionsto exhibit a bias toward binary zeroes, meaning that the data packetshave more binary zeroes than binary ones. Other data packets may havemore binary ones than zeroes, or a balance of binary ones and zeroes.While data packets may each have an individual bias based on data withinthe packets, a bias of the storage cells of the non-volatile memorymedia 110 may be based on some benefit associated with the storage of aparticular binary value or pattern, or some property of the storagecells. One example of a storage cell property, NAND flash storage cellspresently are biased to all binary one values or almost all binary onevalues when provided by a manufacturer. In addition, performing an eraseoperation on the NAND flash storage cells sets the binary values in eachstorage cell to a binary one, such that programming of the storage cellscomprises changing certain storage cells to a binary zero value. Thisbias to all binary one values or almost all binary one values whenprovided by a manufacturer or when erased represents one example of anempty state for storage cells of a non-volatile memory media 110.

Each of the storage elements 216, 218, 220, in one embodiment, storebinary data in a plurality of storage cells that exhibit a bias. Eachstorage cell stores one or more binary bits, or values. Flash memorystorage cells may be single-level cells (“SLC”) that each store a singlebinary bit, or multi-level cells (“MLC”) that each store two or morebinary bits. Examples of storage cells include transistors, capacitors,magnetic elements, mechanical elements, optical elements, and the like.In flash memory, each storage cell is typically a floating-gatetransistor. NRAM, MRAM, DRAM, PRAM, and other types of non-volatilememory may have other types of storage cells, and may store either asingle binary bit or two or more binary bits per storage cell.

In one embodiment, the storage cells in the storage elements 216, 218,220 in an empty or erased state store initial binary values. The initialbinary values represent a bias for the storage cells. For example, thestorage cells may have a physical, electrical, mechanical, or otherquality that causes them to store a certain value by default. In anotherembodiment, the bias may be intentionally selected based on designconsiderations of the non-volatile memory media 110, on securityconsiderations, on compatibility issues, or the like, and may not bebased on a default property of the storage cells.

For example, in one embodiment, the storage cells of the storageelements 216, 218, 220 may each store a binary value of one upondelivery from a manufacturer, and may each be erased to a value of oneprior to being programmed, or written to, as is typical with flashmemory. In another embodiment, the storage cells of the storage elements216, 218, 220 may be biased toward binary zeroes, toward a balance orequal amount of binary ones and zeroes, toward a certain binary valuefor a plurality of bits, toward a binary pattern, or the like.

In certain embodiments, a bias of one or more storage cells may beinfluenced by or based on a state of other storage cells physicallyadjacent to or otherwise in proximity to the one or more storage cells.For example, it may be desirable to bias data stored in storage cells tominimize inter-cell interference between the storage cells and otherstorage cells, or the like. Inter-cell interference can be caused byvoltage differentials between physically adjacent storage cells and, incertain embodiments, biasing data to reduce or minimize the voltagedifferentials between storage cells based on a physical geometry of thestorage cells can reduce inter-cell interference. In one embodiment,storage cells of the non-volatile memory media 110 may have a biastoward a binary pattern that satisfies a predefined voltage differentialthreshold between the storage cells and other physically adjacentstorage cells, or the like.

In addition to local types of inter-cell interference, larger multi-cellstructures, such as bit strings, word lines, or the like, may experienceinter-cell interference. Certain stripes or other patterns in data, suchas stripes of binary ones or of binary zeroes, may interfere with theaccuracy or effectiveness of sense amplifiers and/or other managementcircuitry for these larger, multi-cell structures, and it may beadvantageous to bias data away from such stripes or other patterns.

For certain types of storage cells, such as SLC flash memory, thevoltage level of a storage cell and associated voltage differentialsbetween storage cells may be based on a single bit value for eachstorage cell and biasing data may include biasing toward a binarypattern with minimal transitions between binary one values and binaryzero values within a data packet and/or within a physical region ofstorage cells. For other types of storage cells, such as MLC flashmemory, the voltage level of a storage cell and associated voltagedifferentials between storage cells may be based on groups of bitsforming a sub-pattern or symbol, and biasing data may include biasingtoward a binary pattern with minimal transitions between certainsub-patterns or symbols. One example of using sub-patterns or symbolsincludes binary or Gray-code mapping of multiple binary values toassociated charge levels within MLC storage cells. The bits stored by asingle MLC storage cell, in certain embodiments, may not have adjacentaddresses, but may be stored on different physical pages, logical pages,or the like.

In one embodiment, the bias module 318 biases source data to reduceinter-cell interference as a separate step performed separately from,instead of, or in addition to other biasing techniques. For example,upon flipping, whitening, compressing, relocating, and/or otherwisebiasing source data, separate blocks of source data may still exhibitpatterns that cause inter-cell interference, and the bias module 318 maybias one or more of the separate blocks of source data toward a patternthat minimizes inter-cell interference, or the like.

The bias module 318 biases a packet by changing a bias of the packet tomore closely match a bias of the storage cells of the non-volatilememory media 110. The bias module 318 biases the packets in a reversiblemanner, such that the inverse bias module 332 can convert the packetsback to their original source data values with their original sourcebiases. In one embodiment, the packets that the bias module 318 biasesare sized for storage in a specific logical or physical storage regionor division of the non-volatile memory media 110, such as an eraseblock, a virtual erase block, a page, a virtual page, an ECCchunk/codeword, a division within a page, or the like. In oneembodiment, the bias module 318 selectively biases certain packets basedon a bias of the packets, and may not bias other packets.

Those of skill in the art recognize that the bias module 318 may,alternatively, operate on one or more data segments that form a subsetof a data packet. Similarly, the inverse bias module 332 may operate ondata segments as well. Alternatively, or in addition, in one embodiment,the data packet (or data packet subsets such as a data segment) may besized based on a size of a storage region in the non-volatile memorymedia 110, a size of a bus or buffer, a size of a pipeline 106, 108, anumber of extra bits available for storage of an indicator, or the like.

By biasing data packets toward the bias of the storage cells, the biasmodule 318 increases performance and endurance of the non-volatilememory media 110 and the non-volatile memory device 102. For example,biasing packets to more closely match the bias of the storage cellsdecreases write times and erase times because fewer actual storage cellsmust be changed to execute the operation. It also increases the writablelife of the storage cells because fewer operations that are executed ona storage cell mean that the storage cell will last longer before wearbegins to affect the storage cell performance/reliability. In certainembodiments, biasing data packets may decrease power consumption or haveother additional benefits. Because, in one embodiment, the storage cellsstore initial binary values that satisfy a bias just prior to beingprogrammed or written to, the closer that the data packets match thebias of the storage cells, the fewer the number of storage cells thatare changed to store the data packets, and the more storage cells thatremain in a biased state.

As depicted, the bias module 318 biases the one or more packets prior tosending the packets to the ECC encoder 304. Depending on the method thatthe bias module 318 uses to bias the packets, and on other designconsiderations, in a further embodiment, the bias module 318 may receivedata subsequent to the ECC encoder 304 in the write data pipeline 106,or be placed elsewhere in the write data pipeline 106. For example, incertain embodiments, it may be beneficial to keep ECC data separate fromdata that the bias module 318 biases, while in other embodiments it maybe beneficial for the bias module 318 to bias data that includes ECCdata from the ECC encoder 304.

In one embodiment, the bias module 318 biases one or more data segmentsprior to sending the data segments to the ECC encoder 304. The datasegment may be a grouping of bits smaller than a data packet in oneembodiment. In such an embodiment, the data segment may comprise thewidth in bits/bytes of the write data pipeline 106. Similarly, theinverse bias module 332 may convert biased data segments back to theiroriginal source state after they are read. Biasing and inverse biasing adata segment may facilitate use of the bias module 318 and the inversebias module 332 in a write data pipeline 106 and a read data pipeline108 because the data segment may be sized to match the size (bus width)of data streaming through the pipelines 106,108.

In another embodiment, the bias module 318 may be integrated withanother element of the write data pipeline 106, such as the compressionmodule 312, the encryption module 314, the ECC encoder 304, or the like.The bias module 318 and corresponding inverse bias module 332transparently increase the performance of the non-volatile memory media110 as the bias module 318 biases data packets before they are writtenand the inverse bias module 332 converts the biased data packets back totheir original source state after they are read. In certain embodiments,the order of the stages 302-320 may be altered from the depicted order.There are other workable alterations to the order of the stages 302-320based on particular user requirements, or the like.

The read data pipeline 108 includes an ECC decoder 322 that determinesif a data error exists in ECC blocks a requested packet received fromthe non-volatile memory media 110 by using ECC stored with each ECCblock of the requested packet. The ECC decoder 322 then corrects anyerrors in the requested packet if any error exists and the errors arecorrectable using the ECC. For example, if the ECC can detect an errorin six bits but can only correct three bit errors, the ECC decoder 322corrects ECC blocks of the requested packet with up to three bits inerror. The ECC decoder 322 corrects the bits in error by changing thebits in error to the correct one or zero state so that the requesteddata packet is identical to when it was written to the non-volatilememory media 110 and the ECC was generated for the packet.

In certain embodiments, the ECC decoder 322 may provide errorinformation for correctable errors to the configuration module 352,described below, such as locations of the bits in error, values for thebits in error, and/or other error information. For example, the ECCdecoder 322 may provide an error bias to the configuration module 352,indicating one or more bits of a data set that are in error, or thelike. An error bias, as used herein, is a representation of one or moredetected bit errors in a data set. In one embodiment, an error biasincludes a location or position of a detected bit error in a data set.In another embodiment, an error bias includes a value for a detected biterror. A value for a detected error may include an error corrected valueof a bit in error, an error value of the bit in error, or the like. Forexample, in one embodiment, the ECC decoder 322 may provide theconfiguration module 352 with an uncorrected data set and an error biasindicating locations of detected bit errors and the configuration module352 may determine a known bias by inverting or flipping the bits inthose locations. In another embodiment, for example, the ECC decoder 322may provide the configuration module 352 with an error corrected dataset and an error bias indicating locations of detected bit errors andthe configuration module 352 may determine a read bias by inverting orflipping the bits in those locations.

If the ECC decoder 322 determines that the requested packets containsmore bits in error than the ECC can correct, the ECC decoder 322 cannotcorrect the errors in the corrupted ECC blocks of the requested packetand sends an interrupt. In one embodiment, the ECC decoder 322 sends aninterrupt with a message indicating that the requested packet is inerror. The message may include information that the ECC decoder 322cannot correct the errors or the inability of the ECC decoder 322 tocorrect the errors may be implied. In another embodiment, the ECCdecoder 322 sends the corrupted ECC blocks of the requested packet withthe interrupt and/or the message.

In one embodiment, a corrupted ECC block or portion of a corrupted ECCblock of the requested packet that cannot be corrected by the ECCdecoder 322 is read by the master controller 224, corrected, andreturned to the ECC decoder 322 for further processing by the read datapipeline 108. In one embodiment, a corrupted ECC block or portion of acorrupted ECC block of the requested packet is sent to the devicerequesting the data. The requesting device 155 may correct the ECC blockor replace the data using another copy, such as a backup or mirror copy,and then may use the replacement data of the requested data packet orreturn it to the read data pipeline 108. The requesting device 155 mayuse header information in the requested packet in error to identify datarequired to replace the corrupted requested packet or to replace thedata structure to which the packet belongs. In another embodiment, thenon-volatile memory controller 104 stores data using some type of RAIDand is able to recover the corrupted data. In another embodiment, theECC decoder 322 sends an interrupt and/or message and the receivingdevice fails the read operation associated with the requested datapacket. One of skill in the art will recognize other options and actionsto be taken as a result of the ECC decoder 322 determining that one ormore ECC blocks of the requested packet are corrupted and that the ECCdecoder 322 cannot correct the errors.

In one embodiment, the non-volatile memory controller 104 includes aconfiguration module 352 that sets and adjusts configuration parametersfor the non-volatile memory media 110, such as read voltage thresholdsand the like. In a further embodiment, the configuration module 352 maybe integrated with the non-volatile memory media 110 such that itoperates independently from the read data pipeline 108 and/or the writedata pipeline 106. In certain embodiments, as described in greaterdetail below with regard to the proactive configuration module 424 ofFIG. 4 and FIG. 5, the configuration module 352 proactively determinesone or more configuration parameters for storage cells of thenon-volatile memory media 110 based on media characteristics for thestorage cells in an open loop manner, with little or no feedback fromthe storage cells. In the depicted embodiment, the configuration module352 is in communication with the storage control bus 212 and the storagebus controller 348 to configure storage cells of the non-volatile memorymedia 110 to use various configuration parameters. In anotherembodiment, the configuration module 352 manages configurationparameters and/or settings for the non-volatile memory controller 104and or for the non-volatile memory device 102.

In other embodiments, the configuration module 352 may receive a dataset from the non-volatile memory media 110, either directly orindirectly, to determine configuration parameters for correspondingstorage cells in a closed loop manner, with read data sets as feedbackfrom the storage cells. In certain embodiments, the configuration module352 may receive one or more requested biased packets from the ECCdecoder 322. In a further embodiment, the configuration module 352 mayreceive a data set from the read synchronization buffer 328, directlyfrom the storage I/O bus 210, from the inverse bias module 332, orotherwise. The configuration module 352 is described in greater detailwith regard to FIG. 4. Another embodiment, where the configurationmodule 352 receives input from both the ECC decoder 322 and the inversebias module 332 is described below with regard to FIG. 3B.

In general, the configuration module 352 sets and adjusts one or moreconfiguration parameters for one or more storage cells from thenon-volatile memory media 110, such as setting and adjusting readvoltage thresholds, resistivity thresholds, programming thresholds,erase thresholds, or the like. A read voltage threshold is a voltagelevel that separates discrete values stored in the storage cells of thenon-volatile memory media 110. Different non-volatile memorytechnologies may use different thresholds other than voltages todistinguish between discrete states. Phase change RAM or PRAM, forexample, stores data in chalcogenide glass that has different electricalresistivity in different states. For PRAM, the configuration module 352may determine, set, and/or adjust resistivity thresholds thatdistinguish between discrete storage states. One of skill in the art, inlight of this disclosure, will recognize that the configuration module352 may determine, set, and adjust resistivity thresholds or otherconfiguration parameters in a substantially similar manner to thatdescribed herein with regard to read voltage thresholds.

For SLC storage cells that store a single binary value, the read voltagethreshold is the boundary between a binary one state and a binary zerostate. For example, in one embodiment, a storage cell with a readvoltage level above the read voltage threshold stores a binary one whilea storage cell with a read voltage level below the read voltagethreshold stores a binary zero. Other types of storage cells, such asMLC storage cells, may have multiple read voltage thresholds, todistinguish between more than two discrete states.

For example, in one embodiment, MLC storage cells that store two bitsmay have three read voltage thresholds, separating binary values of 11,01, 00, and 10. The three example read voltage thresholds may be xvolts, y volts, and z volts, described in greater detail below withregard to the read voltage thresholds 662 of FIG. 6C. If the voltageread from a storage cell falls between Vmin and x volts, a binary 11state is indicated. In certain embodiments, Vmin may be a negativevoltage. If the voltage read from a storage cell falls between x voltsand y volts, a binary 01 state is indicated. If the voltage read from astorage cell falls between y volts and z volts, a binary 00 state isindicated. If the voltage read from a storage cell falls between z voltsand Vmax volts, a binary 10 state is indicated.

The voltages for Vmin, Vmax, x, y, z may vary based on the manufacturerof the storage cells. Read voltages, for example, may range between −3.5and 5.8 volts, or between another predefined range of voltages.Similarly, the order of binary state changes 11, 01, 00, and 10 relativeto read voltage thresholds may vary based on the encoding type used,such as a Gray code encoding type, a binary code encoding type, or thelike. One example encoding type is described below with regard to FIG.6C. As described in greater detail with regard to FIG. 6C, although asingle MLC storage cell stores multiple bits, bits from a single storagecell may not have adjacent addresses, and may be included in differentphysical pages, logical pages, or the like. Accordingly, in variousembodiments, the configuration module 352 may manage configurationparameters, such as read voltage thresholds or other storage thresholds,at various granularities, such as per abode/storage state, per page(logical or physical), per erase block (logical or physical), per set ofpages, per ECC chunk/codeword, per wordline, per chip, per die, per dieplane, or the like.

In certain embodiments, instead of referring to a boundary betweendiscrete values, a read voltage threshold comprises a range of voltages(a maximum and a minimum) that indicate a value. A voltage thresholdthat is a range can be adjusted by changing the boundary at either end,or at both ends, of the range. The read voltage thresholds or otherconfiguration parameters for the non-volatile memory media 110, in oneembodiment, are initially set at a default level that may be defined bya manufacturer. Often such configuration parameter default levels areset to accommodate a large range of general purpose uses of thenon-volatile memory media 110. Advantageously, embodiments of theconfiguration module 352 allow the non-volatile memory media 110 to beused most optimally based on more specific use characteristics. Theconfiguration module 352, in certain embodiments, overrides the defaultlevel for one or more configuration parameters, setting the one or moreconfiguration parameters to a different level based on mediacharacteristics of the non-volatile memory media 110. The configurationmodule 352 may set the configuration parameters to a level thatdecreases the amount of errors that the non-volatile memory media 110encounters when compared to the default level, to a level that increasesthe amount of errors that may be detected and corrected when compared tothe default level, to a level that increases the number of input/outputoperations per second (“IOPS”) of the non-volatile memory media 110 whencompared to the default level, to a level that increases the usable lifeof the non-volatile memory media 110 when compared to the default level,and/or that otherwise improves the utility of the non-volatile memorymedia 110 when compared to the default level.

The read voltage levels of storage cells, and other configurationparameters, can also shift over time, due to leakage and otherdisturbances of the non-volatile memory media 110. The rate of leakagecan also increase with the wear and age of the non-volatile memory media110. If the read voltage level of a storage cell shifts past the readvoltage threshold, a data error occurs, as the value of the data readfrom the storage cell is different than the value of the data written tothe storage cell. The configuration module 352, in one embodiment,adjusts a read voltage threshold or other configuration parameter forone or more storage cells from the non-volatile memory media 110 tocompensate for shifts in the read voltage levels of the storage cells.By proactively and/or dynamically adjusting read voltage thresholds, theconfiguration module 352 can increase the retention rate for and/or thereliability of data stored in the non-volatile memory media 110 andextend the useable lifetime of the non-volatile memory media 110 itself,improving the utility of the non-volatile memory media 110.

The configuration module 352, in one embodiment, uses a known bias ofthe data set or packet from the non-volatile memory media 110 to adjustthe read voltage threshold or other configuration parameter. Asdescribed above with regard to the bias module 318, a bias is apreference, probability, tendency, or desirability of values for bitswithin a set of bits to exhibit a specific data pattern. A bias may be anatural property, a designed attribute, a property of performing anoperation on non-volatile memory media, or a random occurrence. A biasmay be toward binary ones, toward binary zeroes, toward a balance ofbinary ones and zeroes, toward a certain binary value for certain bits,toward a specific ratio of binary ones and binary zeroes, toward abinary pattern, or the like.

In one embodiment, the data set or packet that the configuration module352 receives has a known bias. The data set or packet has a known biasfor one of at least three reasons. First, the data set or packet mayhave a known bias because the bias module 318 biased the data set orpacket when the data set or packet was written. In one embodiment, thebias module 318 and/or the inverse bias module 332 cooperate with theconfiguration module 352, communicating the known bias to theconfiguration module 352. Second, the data set or packet may have aknown bias because the data set or packet is read from a virgin,unwritten region of the non-volatile memory media 110. For example, inone embodiment, virgin, unwritten regions of the non-volatile memorymedia 110 may typically have a known bias of exclusively binary ones orexclusively binary zeroes in an unwritten state. Third, the data set orpacket may have a known bias because the ECC decoder 322 has correctedthe data set or packet and has determined the original, correct valuesof one or more bits of the data set that were in error. The correctvalues for the bits in the data set comprise this known bias. Adeviation from the known bias caused by errors in the data set is anerror bias.

The configuration module 352, in one embodiment, determines that a readbias for the data set or packet deviates from the known bias, anddetermines a direction of deviation for the data set based on adifference between the read bias and the known bias. In a furtherembodiment, the configuration module 352 adjusts the read voltagethreshold, or another read threshold such as a resistivity threshold,for storage cells corresponding to the data set based on the directionof deviation. For example, in one embodiment, the configuration module352 may lower the read voltage threshold from the previous read voltagethreshold to a new read voltage threshold for the storage cells if thedata set has more binary zeroes than expected based on the known bias.For MLC storage cells, in one embodiment, a data set may include datafrom different addresses, different pages, or the like so that the dataset includes all data that the associated storage cells store. Theconfiguration module 352 may base a read voltage threshold adjustment onknown characteristics of the storage cells, such as an encoding typeused for the storage cells, based on a physical and/or electricalarchitecture of the storage cells, or the like. In a further embodiment,the configuration module 352 may transform, translate, or combine datafrom different addresses or pages to facilitate a determination of aknown bias, a read bias, and/or a deviation from a known bias for MLCstorage cells. In another embodiment, for MLC storage cells, theconfiguration module 352 may adjust a read voltage threshold for the MLCstorage cells based on a subset of the data stored by the MLC storagecells.

The configuration module 352, in one embodiment, may request that thedata set be re-read with the new read voltage threshold. Theconfiguration module 352 may determine whether the re-read data set hasa read bias that deviates from the known bias, and may iterativelyadjust the read voltage threshold to a new read voltage threshold untilthe read bias of the data set no longer deviates from the known biasmore than a threshold amount (which may be zero), until the ECC decoder322 can correct errors in the data set, or the like. In one embodiment,the configuration module 352 stores the new read voltage threshold suchthat the new read voltage threshold is persistent for subsequent datareads from the non-volatile memory media 110. In a further embodiment,the non-volatile memory media 110 stores the new read voltage thresholdfor subsequent data reads.

The configuration module 352, in one embodiment, may monitor the readbias of each packet read and compare the bias of the packet or otherdata set to the known bias in response to a read request. In a furtherembodiment, the configuration module 352 may monitor the read bias ofeach packet read and may compare the bias of the data set or packet tothe known bias in response to a data error, such as, for example, anuncorrectable bit error that the ECC decoder 322 cannot correct, or thelike. In a further embodiment, the configuration module 352 may notmonitor the read bias of each packet read and may determine and comparethe bias of the data set or packet to the known bias exclusively inresponse to a data error. As described below with regard to theproactive configuration module 424 of FIGS. 4 and 5, in certainembodiments, the configuration module 352 sets or adjusts a read voltagethreshold or other configuration parameter proactively, based on mediacharacteristics instead of, or in addition to, adjustments based on readdata sets or packets.

In one embodiment, the non-volatile memory controller 104 may read datain a data packet from multiple channels, storage elements, die, chips,physical erase blocks (“PEBs”), groupings of storage cells, or the likewithin the non-volatile memory media 110, each of which may haveindependent read voltage thresholds. The manufacturer of the channels,storage elements, die, chips, and/or grouping of storage cells may makethe read voltage thresholds for each channel, storage element, die,chip, and/or grouping of storage cells independently adjustable by thenon-volatile memory controller 104. Alternatively, or in addition, themanufacturer of the channels, storage elements, die, chips, and/orgrouping of storage cells may make the read voltage thresholds forgroups of channels, groups of storage elements, groups of die, groups ofchips, and/or groups of groupings of storage cells adjustable by thenon-volatile memory controller 104 as separate groups.

In one embodiment, the ECC encoder 304 creates independent ECC checkbitsfor each channel, storage element, die, chip, PEB, or other grouping ofstorage cells. The ECC checkbits are stored with the data on aparticular grouping of storage cells rather than being distributedacross multiple groupings. If ECC checkbits are created and storedindependently for each grouping of storage cells, the configurationmodule 352, in response to a data error, may use the ECC checkbits andthe known architecture for how an ECC checkbits are written to thegroupings of storage cells to determine in which grouping of storagecells the data error occurred, and adjust the read voltage thresholds ofthose groupings. If ECC checkbits for the data packet are stored acrossmultiple groupings of storage cells, the configuration module 352 mayseparately check the read biases of data sets from each grouping ofstorage cells and adjust one or more of the corresponding read voltagethresholds. An array of storage elements with multiple channels isdescribed in greater detail with regard to FIGS. 6A and 6B.

In one embodiment, the read data pipeline 108 includes an inverse biasmodule 332 that receives one or more requested biased packets from theECC decoder 322, either directly or indirectly, and converts the one ormore requested packets back to their original source form by reversingthe biasing process of the bias module 318 prior to sending the one ormore requested packets to the depacketizer 324. In one embodiment, theinverse bias module 332 may use one or more indicators stored by thebias module 318 to convert the biased packets back to their originalsource data. In certain embodiments, the inverse bias module 332 mayprovide a known bias, a read bias, and/or a deviation from a known biasfor a packet or other data set to the configuration module 352, asdescribed below with regard to FIG. 3B.

In a further embodiment, the inverse bias module 332 converts the biasedpackets back to their original source data without using an indicator.Instead of using an indicator, the inverse bias module 332 may implementan algorithm that is the inverse operation of the bias module 318. Thisalgorithm may inverse the bias for each data packet received and/or aselect number of data packets received. In the depicted embodiment, theinverse bias module 332 is located between the ECC decoder 322 and thedepacketizer 324. In a further embodiment, the inverse bias module 332may be located elsewhere in the read data pipeline 108, based on thelocation of the bias module 318 in the write data pipeline 106.

As with the write data pipeline 106, the stages of the read datapipeline 108 may be rearranged and other orders of stages within theread data pipeline 108 are possible. The non-volatile memory controller104 includes control and status registers 340 and corresponding controlqueues 342. The control and status registers 340 and control queues 342facilitate control and sequencing commands and subcommands associatedwith data processed in the write and read data pipelines 106, 108. Forexample, a data segment in the packetizer 302 may have one or morecorresponding control commands or instructions in a control queue 342associated with the ECC encoder 304. As the data segment is packetized,some of the instructions or commands may be executed within thepacketizer 302. Other commands or instructions may be passed to the nextcontrol queue 342 through the control and status registers 340 as thenewly formed data packet created from the data segment is passed to thenext stage.

Commands or instructions may be simultaneously loaded into the controlqueues 342 for a packet being forwarded to the write data pipeline 106with each pipeline stage pulling the appropriate command or instructionas the respective packet is executed by that stage. Similarly, commandsor instructions may be simultaneously loaded into the control queues 342for a packet being requested from the read data pipeline 108 with eachpipeline stage pulling the appropriate command or instruction as therespective packet is executed by that stage. One of skill in the artwill recognize other features and functions of control and statusregisters 340 and control queues 342.

The non-volatile memory controller 104 and or non-volatile memory device102 may also include a bank interleave controller 344, a synchronizationbuffer 346, a storage bus controller 348, and a multiplexer (“MUX”) 350.

Configuring Storage Cells

FIG. 3B is a schematic block diagram illustrating another embodiment 301of a non-volatile memory controller 104. In the depicted embodiment 301,the non-volatile memory controller 104 includes a device factor module354, the inverse bias module 332, the ECC decoder 322, and theconfiguration module 352. Although not depicted in FIG. 3B, thenon-volatile memory controller 104 of the embodiment illustrated in FIG.3B may also, in certain embodiments, include one or more additionalmodules or other elements from the non-volatile memory controller 104depicted in FIG. 3A, as described above.

In the depicted embodiment 301, the configuration module 352 receivesinputs from the inverse bias module 332, the ECC decoder 322, and thedevice factor module 354 and the configuration module 352 determines aconfiguration parameter adjustment 358 based on the inputs. In otherembodiments, the configuration module 352 may receive inputs from justthe inverse bias module 332, from just the ECC decoder 322, from justthe device factor module 354, or from a different combination of theinverse bias module 332, the ECC decoder 322, and/or the device factormodule 354.

The inverse bias module 332, in one embodiment, provides a known biasand/or an actual read bias of a data set to the configuration module352. The inverse bias module 332 may provide the known bias as anexpected bias based on a reversible biasing algorithm that the biasmodule 318 applies to data written to the non-volatile memory media 110.The expected bias, in certain embodiments, may be an exact bias, wherethe bias module 318 uses a reversible biasing algorithm that biases datato exactly match a bias. For example, the bias module 318 may addpadding data to a data set so that the data set has an exact balance ofbinary ones and binary zeroes, or the like, and the known bias may beexact.

In another embodiment, the inverse bias module 332 may provide theexpected bias as a range, a distribution, an average, an estimate, orthe like based on the reversible biasing algorithm that the bias module318 applies to data. For example, the inverse bias module 332 maymeasure or learn an expected bias over time as the inverse bias module332 applies an inverse biasing algorithm to data read from thenon-volatile memory media 110. In one embodiment, the expected bias maybe mathematically or otherwise derived from the reversible biasingalgorithm of the bias module 318 as a range or distribution of possibleor likely biases.

For example, where the bias module 318 biases data toward a balance ofone half binary ones and one half binary zeroes, which may also bereferred to as a direct current (“DC”) balance, a range of actual biasesfor biased data may range between about forty-six percent binary onesand fifty-four percent binary ones, or the like. The known bias and theread bias of the data set, in other embodiments, may also be based onmulti-bit symbols or patterns of bits instead of being based exclusivelyon individual binary ones and zeroes, or the like. While the inversebias module 332, in the depicted embodiment 301, provides input to theconfiguration module 352, in certain embodiments, the bias module 318may provide an expected bias to the configuration module 352 as a knownbias, the known bias may be hard coded or programmed into theconfiguration module 352, or the like.

In one embodiment, the inverse bias module 332 provides a read bias of adata set read from the non-volatile memory media 110 to theconfiguration module 352. For example, as the inverse bias module 332converts biased data packets or other data sets back to their originalsource form by reversing the biasing process of the bias module 318, theinverse bias module 332 may determine, measure, or detect the read biasof the data packets or other data sets. The inverse bias module 332 maydetermine a read bias prior to, during, or after reversing the biasingprocess, depending on the biasing process used. In certain embodiments,if the inverse bias module 332 determines that a read bias of a data setdeviates from the known/expected bias of the data set, the inverse biasmodule 332 may provide the data set to the configuration module 352 tomake a configuration parameter adjustment 358 to storage cells of thedata set so that the data set may be re-read. In other embodiments, asdescribed above with regard to FIG. 3A, the configuration module 352 mayadjust a read voltage threshold for a data set before the inverse biasmodule 332 receives the data set. Other arrangements of theconfiguration module 352, the inverse bias module 332, and the ECCdecoder 322 may also be used.

The ECC decoder 322, in one embodiment, provides a known bias and/or aread bias for a data set to the configuration module 352. The ECCdecoder 322 may provide a known bias for a data set having a correctstate of bits for the data set. For example, once the ECC decoder 322has corrected one or more correctable bit errors in a data set, the ECCdecoder 322 may provide the error corrected state of the bits of thedata set to the configuration module 352 as a known bias with which thedata set was written to the non-volatile memory media 110. The ECCdecoder 322, in a further embodiment, may provide the read bias for adata set as an error bias that indicates one or more bits of a data setthat were in error when the data set was read from the non-volatilememory media 110.

Because the ECC decoder 322, for correctable errors, determines theexact, original, correct values of bits (known bias) of a data set andan exact location of bits in error (error bias) of the data set theconfiguration module 352 can determine an exact deviation of the dataset from the known bias. For this reason, in certain embodiments, theconfiguration module 352 may make more precise configuration parameteradjustments 358 using a known bias and an error bias from the ECCdecoder 322, when available, than using an expected bias and a read biasfrom the inverse bias module 332.

The configuration module 352, in one embodiment, uses a known biasand/or an error bias for a data set from the ECC decoder 322 in responseto one or more correctable bit errors in the data set. In a furtherembodiment, the configuration module 352 uses an expected bias that isbased on a reversible biasing algorithm as a known bias. In certainembodiments, the expected bias is used as the known bias in response toone or more uncorrectable bit errors in the data set. An error bias fromthe ECC decoder 322 may not be available to the configuration module 352for uncorrectable bit errors because the uncorrectable bit errorcondition makes the bias undefined. For uncorrectable bit errors in adata set, in certain embodiments, the read bias of the data set maydeviate from the known, expected bias for the data set more than forcorrectable bit errors, because of the greater severity of the errors.Due to the greater magnitude of deviation of the read bias of a data setfrom the known, expected bias of the data set for uncorrectable biterrors, the bias information from the inverse bias module 332 mayprovide a better indicator of a direction for a configuration parameteradjustment 358 for uncorrectable bit errors than for correctable biterrors.

The device factor module 354, in one embodiment, provides one or morestatistics for the non-volatile memory device 102 to the configurationmodule 352. The configuration module 352, in certain embodiments, maymake a configuration parameter adjustment 358 based on the one or morestatistics, may supplement information from the inverse bias module 332and/or the ECC decoder 322 with the one or more statistics, or the like.The one or more statistics for the non-volatile memory device 102, inone embodiment, include statistics that may affect read voltages orother configuration parameters of storage cells of the non-volatilememory device 102. For example, in certain embodiments, the one or morestatistics may include a temperature for the non-volatile memory device102, an error rate for the non-volatile memory device 102 (such as anuncorrectable bit error rate “UBER,” a raw bit error rate “RBER,” or thelike), a program/erase cycle count for the non-volatile memory device102, a storage request latency for the non-volatile memory device 102(such as an average, maximum, or other storage request executionlatency), an age of the non-volatile memory device 102, and/or otherstatistics or characteristics.

In the depicted embodiment 301, the device factor module 354 receivesinput from one or more sensors 356. The one or more sensors 356 eachdetect a statistic or characteristic for the non-volatile memory device102, such as temperature, moisture, movement, and/or other statistics.For example, in various embodiments, the one or more sensors 356 mayinclude a temperature sensor, a moisture sensor, an accelerometer,and/or another type of sensor for the non-volatile memory device 102. Inone embodiment, the device factor module 354 and/or the configurationmodule 352 may receive one or more statistics for the non-volatilememory device 102 from one or more other modules or elements. Forexample, the device factor module 354 and/or the configuration module352 may receive an error rate for the non-volatile memory device 102,such as a UBER, a RBER, or the like, from the ECC decoder 322.

The configuration module 352, in various embodiments, may base aconfiguration parameter adjustment 358 on a single input or on acombination of inputs from the inverse bias module 332, the ECC decoder322, and/or the device factor module 354. In certain embodiments, one ormore inputs from the inverse bias module 332, the ECC decoder 322,and/or the device factor module 354 may not be available for a data set.For example, the ECC decoder 322 may not provide an error bias and aknown bias for a data set with an uncorrectable bit error, the inversebias module 332 may not provide a known, expected bias or a read biasfor a data set during a learning period while the inverse bias module332 is determining an expected bias, the device factor module 354 maynot provide one or more statistics during an initial startup period, orthe like.

In one embodiment, the configuration module 352 bases a configurationparameter adjustment 358 on a best available input according to apredefined hierarchy or ranking of inputs. For example, theconfiguration module 352 may base a configuration parameter adjustment358 on a known bias and error bias from the ECC decoder 322 ifavailable; on a known, expected bias and a read bias from the inversebias module 332 if input from the ECC decoder 322 is not available; andon one or more statistics from the device factor module 354 if inputfrom both the ECC decoder 322 and the inverse bias module 332 isunavailable.

In a further embodiment, the configuration module 352 may make a randomconfiguration parameter adjustment 358, in response to a data error orthe like, if input from each of the inverse bias module 332, the ECCdecoder 322, and the device factor module 354 is unavailable. Forexample, the configuration module 352 may try a configuration parameteradjustment 358 in one direction, re-read the data set and check forerrors, and try a configuration parameter adjustment 358 in the otherdirection if the error persists.

In another embodiment, the configuration module 352 may base aconfiguration parameter adjustment 358 on multiple inputs by combiningthe inputs from the inverse bias module 332, the ECC decoder 322, and/orthe device factor module 354. The configuration module 352 may scale theinputs, weight the inputs, convert the inputs to common units, or thelike to facilitate combination of the inputs. For example, theconfiguration module 352, in one embodiment, may convert each of theinputs to individual preliminary threshold adjustments, and then sum thepreliminary threshold adjustments to provide a configuration parameteradjustment 358. The configuration module 352, in the example, may weighteach preliminary threshold adjustment based on a predefined hierarchy orranking of the associated inputs. For example, if a known bias and anerror bias from the ECC decoder 322 indicates a configuration parameteradjustment 358 in one direction and the known, expected bias and theread bias from the inverse bias module 332 indicates a configurationparameter adjustment 358 in the other direction, the input with greaterweight or priority in the predefined hierarchy or ranking will dictatethe direction of the configuration parameter adjustment 358.

FIG. 4 depicts one embodiment of a configuration module 352. In thedepicted embodiment, the configuration module 352 includes a data setread module 402, a deviation module 404, a direction module 406, anadjustment module 408, a persistence module 410, an ECC module 412, adistribution module 414, a data set source module 422, a proactiveconfiguration module 424, and a write voltage module 416. The writevoltage module 416 may be integrated with the configuration module 352or separate from the configuration module 352. As described above withregard to the configuration module 352 of FIG. 3A and FIG. 3B, theconfiguration module 352 may be part of the write data pipeline 106,part of the read data pipeline 108, part of the non-volatile memorymedia 110, or the like, such that the configuration module 352 mayadjust a read voltage threshold and/or another configuration parameterfor one or more storage cells of the non-volatile memory media 110.While specific embodiments are described using a read voltage thresholdas an example configuration parameter, the configuration module 352 maysimilarly determine and adjust other configuration parameters.

The configuration module 352, in one embodiment, sets configurationparameters proactively with an open loop model using the proactiveconfiguration module 424. In another embodiment, the configurationmodule 352 sets configuration parameters reactively with a closed loopmodel using the data set read module 402, the deviation module 404, thedirection module 406, and/or the adjustment module 408. In certainembodiments, the configuration module 352 may make several layers orphases of adjustments to configuration parameters, determiningconfiguration parameters proactively using the proactive configurationmodule 424 and adjusting the configuration parameters reactively as thedata set read module 402 reads data sets from the non-volatile memorymedia 110.

In one embodiment, the data set read module 402 reads a data set fromstorage cells of the non-volatile memory media 110. The data set readmodule 402 may read the data set either directly or indirectly from thenon-volatile memory media 110. For example, in one embodiment, the dataset read module 402 may receive the data set from another module orelement in the read data pipeline 108, the non-volatile memory media110, or the like.

In one embodiment, the data set read module 402 reads the data set inresponse to a testing operation and the data set may be a sample dataset read as part of the testing operation. In a further embodiment, thedata set read module 402 reads the data set in response to a readrequest from a client and the data set may be a data set that the clientrequested. The data set, in one embodiment, may be a full packet, aportion of a packet, or the like. In another embodiment, a size of thedata set may be set by the test operation, by a read request from aclient or the like. In a further embodiment, the data set may be rawdata from the non-volatile memory media 110, independent of packets orother data structures.

The data set, in a further embodiment, was originally stored in thestorage cells with a known bias. For example, the data set may be from apacket that the bias module 318 biased, may be from storage cells of thenon-volatile memory media 110 that are in a virgin state, storingdefault data or other data programmed to the non-volatile memory media110 with a known bias for example by a manufacturer of the non-volatilememory media 110, or the like.

In one embodiment, the data set may be sized relative to a biasingscheme that the bias module 318 employs to bias packets. For example, inone embodiment, the data set may be sized based on the period of adeterministic sequence, such as a pseudorandom binary sequence that thebias module 318 uses to bias packets. The closer the size of the dataset is to an integer multiple of the period of the pseudorandom binarysequence, the more likely it is that the bias of the resulting data setwill match the known bias. In a further embodiment, the bias module 318may guarantee that a data set of a predefined size has a bias that doesnot deviate from the known bias by more than a threshold amount. Thethreshold amount may range from zero to a given integer value orpercentage value.

As described above, a bias is a preference, probability, or tendency ofvalues for bits within a set of bits to exhibit a specific data pattern.In one embodiment, the known bias is a known ratio of binary ones andbinary zeroes within a set of bits or groupings of sets of bits. Theknown ratio, in one embodiment, may be expressed as a proportion orpercentage between zero and one, a ratio of zero representing a bias ofexclusively one value and a ratio of one representing a bias ofexclusively the other value. In one embodiment, the known ratio isgreater than zero and less than one, meaning that the known ratio isoffset between a ratio of exclusively one binary value and a ratio ofexclusively the opposite binary. If the known ratio is greater than zeroand less than one, a deviation in the read bias of the data set mayoccur in either direction from the known ratio and still remaindetectable by the configuration module 352.

In the depicted embodiment, the data set read module 402 includes amonitor module 418 and a read error module 420. The data set read module402, in one embodiment, may read the data set using the monitor module418 and/or the read error module 420. In one embodiment, the monitormodule 418 monitors data sets that are read from the non-volatile memorymedia 110 in response to read requests from a computer 112 or otherclient 114. The monitor module 418 may monitor each data set that isread from the non-volatile memory media 110 or may select certain datasets that are read from the non-volatile memory media 110, at predefinedintervals, in response to a command or directive from a storage client,or the like. By using the monitor module 418 to monitor data sets thatare read from the non-volatile memory media 110, the configurationmodule 352 may adjust read voltage thresholds for the non-volatilememory media 110 dynamically, preventing uncorrectable data errors fromoccurring.

In one embodiment, the read error module 420 reads the data set inresponse to a data error identified in the data set. For example, theECC decoder 322 or another module may determine that a data error hasoccurred. In one embodiment, the data error is an uncorrectable biterror that the ECC decoder 322 does not have enough information tocorrect. Specifically, the ECC decoder 322, in one embodiment, isconfigured to detect and correct up to a certain number of bits (# ofBits in Error—#BER) in error in a data set. When the number of bits inerror exceeds the #BER, the ECC decoder 322 may signal an uncorrectabledata error, an uncorrectable bit error, or the like.

The data error may occur due to a shift in a voltage level retained inone or more storage cells of the non-volatile memory media 110. Thisretained voltage level of a storage cell is referred to herein as a readvoltage level. The read error module 420, in one embodiment, reads thedata set as part of a testing operation. The configuration module 352may conduct the testing operation in response to the data error, inresponse to a scheduled maintenance operation, in response to an initialcalibration operation, or the like. The data set used by the read errormodule 420 may come from a client-requested packet, or may be sampledata read as part of the testing operation.

In certain embodiments, the data set read module 402, when reading adata set of sample data in response to a testing operation,periodically, during monitoring, or the like, may size the sample dataset to fit within excess read bandwidth of the non-volatile memory media110. By sizing sample data to fit within excess read bandwidth of thenon-volatile memory media 110, in one embodiment, reading the sampledata may not affect a read bandwidth for servicing read requests to thenon-volatile memory media 110 or a read throughput of the non-volatilememory media 110. In one embodiment, the data set read module 402 mayread a data set from the non-volatile memory media 110 with a greateramount of data than is requested by a read request to provide a greatersample size of bits for the configuration module 352 to use to determinean adjustment to a read voltage threshold, or the like. A sample sizethat is greater than an amount of data requested, in certainembodiments, may improve the accuracy of a read voltage thresholdadjustment.

For example, if a user application requests 512 bytes of data, and thenon-volatile memory media 110 can read 800 bytes of data in a readrequest at substantially the same speed as 512 bytes of data, in oneembodiment, the data set read module 402 may read a data set of 800bytes for adjusting a read voltage threshold, and provide the requested512 bytes (a subset of the 800 byte data set) to the user applicationwithout affecting the read time of the operation. In one embodiment, thedata set read module 402 sets a minimum data set request size andretrieves at least the minimum data set request size amount of data foreach read request, even if the read request is for less than the minimumdata set request size. The minimum data set request size, in certainembodiments, may be selected to fit within a boundary of one or more ECCchunks/codewords, one or more pages, one or more erase blocks, withinexcess bandwidth of the non-volatile memory media 110, or the like. Inone embodiment, the minimum data set request size may be selected basedon an architecture or geometry of the non-volatile memory media 110, theread data pipeline 108, or the like.

In one embodiment, the deviation module 404 determines that a read biasfor a data set deviates from a known bias with which the data set wasoriginally stored. The read bias of the data set deviates from the knownbias when there is a difference between the read bias and the knownbias. In one embodiment, where the known bias is exact, such as wherethe known bias includes error corrected bit values or where the biasmodule 318 biases to an exact bias, the deviation module 404 maydetermine that any difference between a read bias and the known biascomprises a deviation from the known bias. In other embodiments, theknown bias may include an average bias, an estimated bias, adistribution of biases, a range of biases, or the like. The deviationmodule 404, in these embodiments, may determine that a read bias outsideof a range or distribution of known biases, at least a predefineddeviation threshold away from a known bias, or the like deviates fromthe known bias.

In one embodiment, the difference between the read bias of the data setand the known bias may be a difference in the ratios of binary ones andbinary zeroes. In other embodiments, the difference between the bias ofthe data set and the known bias may be a difference in a binary pattern,a difference in multi-bit binary symbols, or the like. As describedabove with regard to FIG. 3B, in various embodiments, the deviationmodule 404 may receive an original, known bias and/or a read bias for adata set from the ECC decoder 322, from the inverse bias module 332, orthe like.

The deviation module 404, in one embodiment, determines whether the readbias of the data set deviates from the known bias by comparing the readbias to the known bias. The deviation module 404 may compare the readbias to the known bias by counting the number of binary ones and thenumber of binary zeroes in the data set to determine the ratio of binaryones and binary zeroes in the data set and comparing that ratio to aratio of the known bias. In a further embodiment, the deviation module404 may search for and/or count the occurrences of an expected patternor other expected attribute of the known bias and compare the results ofa similar search and/or count in the data set to the expected attribute.In certain embodiments, the ECC decoder 322 indicates to the deviationmodule 404 that the read bias of the data set deviates from the knownbias by providing an error bias for the data set to the configurationmodule 352, or the like.

In embodiments where the known bias includes a pattern of bits,multi-bit binary symbols, or the like, the deviation module 404 mayperform a transform on bits of the data set, may analyze a subset ofbits of the data set, or the like to determine whether the read bias ofthe data set deviates from the known bias. For example, the deviationmodule 404 may perform a transform based on an encoding type used forstorage cells of the non-volatile memory media 110, such as a Gray codeencoding type, a binary code encoding type, or the like. The transform,in certain embodiments, may be based on a physical and/or electricalarchitecture of the storage cells of the non-volatile memory media 110.

For example, as described below with regard to FIG. 6C, a multi-levelstorage cell stores at least a most significant bit (“MSB”) and a leastsignificant bit (“LSB”). In certain embodiments, the MSB and the LSB,though part of the same physical multi-level storage cell, may beassigned to different pages of the non-volatile memory media 110. Incertain embodiments, a plurality of the multi-level storage cells areorganized on the non-volatile memory media 110 (such as NAND flash forexample) as a physical page. In certain non-volatile memory media 110, aphysical page is the smallest unit that can be written to thenon-volatile memory media 110. In such embodiments, a multi-levelstorage cell may be associated with a page pair. A page pair is a pairof pages (upper and lower) that are associated with a single set ofphysical multi-level storage cells. For example, a multi-level storagecell may be associated with a page pair that includes an upper page anda lower page. An upper page may be associated with the MSBs, and thelower page may be associated with the LSBs, or vice versa.

Thus, the MSB and LSB in the same multi-level storage cell may havedifferent addresses in the storage device 102. In certain embodiments,the upper page includes the MSBs of a plurality of multi-level storagecells, and the lower page includes the LSBs of the same multi-levelstorage cells. Writes directed to the upper page may therefore causechanges only in the MSBs of the associated multi-level storage cells,while writes directed to the lower page cause changes only in the LSBsof the associated multi-level storage cells.

As described in greater detail below with regard to FIG. 6C, in certainembodiments, the data set read module 402 may read a data set thatincludes only a subset of the bits stored by a grouping of multi-levelstorage cells, and the deviation module 404 may determine whether or notthe read bias of the data set deviates from the known bias based on thesubset of the bits. For example, a data set may include only data valuesfrom LSBs (lower pages), only values from MSBs (upper pages), or thelike. In another embodiment, the deviation module 404 may determinewhether or not a read bias of a data set deviates from a known biasbased at least partially on an encoding type used for storage cells ofthe non-volatile memory media 110, a physical and/or electricalarchitecture of the storage cells of the non-volatile memory media 110,or the like. In other embodiments, the deviation module 404 may performa transform on a data set that may combine data from different pages toinclude both LSB and MSB bits in a single data set, to coordinate LSBand MSB bits and/or pages from different data sets, or the like.

The deviation module 404, in one embodiment, checks the read bias ofeach data set that the data set read module 402 reads. For example, ifthe data set read module 402 uses the monitor module 418, the deviationmodule 404 may monitor the read biases of data sets regularly as theyare read from the non-volatile memory media 110. The monitor module 418,in one embodiment, may compare read biases of each data set that isrequested by a client. In a further embodiment, the monitor module 418may check read biases of requested data sets for example at regularintervals, and/or in response to a command, or the like. In anotherembodiment, if the data set read module 402 uses the read error module420, the deviation module 404 may check the read bias of a data set inresponse to a data error, as part of a testing operation, or the like.

In one embodiment, the direction module 406 determines a direction ofdeviation for the data set. The direction of deviation, in oneembodiment, is a difference between the read bias of the data set andthe known bias. The direction or difference may be represented as avalue, a sign (e.g., positive or negative), a relationship (e.g.,greater than, less than), a direction (e.g., up, down), or the like. Thedirection module 406, in certain embodiments, may determine a directionof deviation based on an encoding type used for storage cells of thenon-volatile memory media 110, based on a physical and/or electricalarchitecture of the storage cells of the non-volatile memory media 110,or the like. For example, the direction module 406 may examine the biasdeviation in the data set to determine a direction of deviation based ona media type (2-bit MLC, 3-bit MLC, n-bit-MLC), which page of amulti-phase programming model was read, an encoding type for thenon-volatile memory media 110 (such as a Gray code encoding type, abinary code encoding type, or the like), and/or a magnitude of thedetermined deviation.

The direction module 406, in one embodiment, may determine the directionby subtracting a ratio, proportion, or other representation of the knownbias from a representation of the read bias of the data set. Forexample, in one embodiment, the direction module 406 may subtract theproportion of binary ones, zeroes, multi-bit binary symbols, or the likethat are expected based on the known bias from the proportion of binaryones, zeroes, multi-bit binary symbols, or the like that are in the dataset. Depending on whether ratios of binary ones are compared or ratiosof binary zeroes are compared and whether a high voltage represents abinary one or a binary zero, or other specific architectures of thestorage cells, the direction module 406 may invert the difference orperform another transform to determine the direction.

In embodiments where an error bias from the ECC decoder 322 isavailable, the direction module 406 may determine the direction ofdeviation based on one or more bits of the data set that are in error,as indicated by the error bias. In other embodiments, as described abovewith regard to FIG. 3B, the direction module 406 may combine directionsbased on input from the inverse bias module 332, the ECC decoder 322,and/or the device factor module 354 to determine a direction ofdeviation, or the like.

In one embodiment, a binary zero is represented by a voltage below theread voltage threshold and a binary one is represented by a voltageabove the read voltage threshold. In one example, a data set is storedwith a known bias of 0.5, representing that the expected bias of thedata set should be one half binary ones, or DC balanced. In thisexample, the data set is read from the storage cells and the data sethas a read bias of 0.7, meaning that seventy percent of the data bitsare binary ones. To determine the direction, in one embodiment, thedirection module 406 subtracts the expected bias, 0.5, from the readbias of the data set, 0.7, for a direction of 0.2. The direction may bethe entire result (e.g., “0.2”), the sign of the result (e.g.,“positive”), a relationship (e.g., “greater than”), a direction, (e.g.,“up”), or another indicator that represents the difference between theexpected bias of 0.5 and the read bias of 0.7.

In another example, if the read bias of the data set is 0.3, meaningthat thirty percent of the data bits are binary ones, the directionmodule 406, in one embodiment, would subtract the expected bias, 0.5,from the read bias of the data set, 0.3, for a difference of −0.2. Inthis example, the direction would be the opposite of the first example,“−0.2,” “negative,” “less then,” “down,” or the like.

Because the expected bias is known, comparing a read bias relative theknown bias indicates that certain bits which should have satisfied theknown bias presently do not, which may be due to a data error or due tochanges in the voltage level stored in the storage cells after they werewritten. In addition, determining that the difference is positive ornegative indicates whether the read voltage should be increased ordecreased such that a re-read of the data set will result in a read biasthat is the same as, or comes closer to the known bias. In oneembodiment, the configuration module 352 adjusts the read voltage levelin the same direction as the direction indicated by the direction module406.

Advantageously, having an indication as to which direction to adjust theread voltage threshold provides a significant reduction in time andresources needed to identify a new adjusted read voltage level. If thedirection in which to make a read voltage threshold was unknown,identifying a new read voltage threshold may require a labor and timeintensive process of trial and error as different possible read voltagethresholds are set and then tested and then adjusted as needed. Theprocess may be used to find a read voltage threshold that results in are-read of the data packet substantially matching the known bias.

In one embodiment, the adjustment module 408 adjusts a read voltagethreshold for the storage cells of the non-volatile memory media 110based on the direction of deviation that the direction module 406determines. The adjustment module 408, in one embodiment, may adjust theread voltage threshold in the direction of deviation, away from thedirection of deviation, or the like. For example, in one embodiment, theadjustment module 408 may raise the read voltage threshold from aprevious read voltage threshold in response to the direction module 406detecting more binary ones than expected in the known bias and lower theread voltage threshold in response to fewer binary ones than expected.While the relative directions may change based on characteristics of thestorage cells of the non-volatile memory media 110 and the storagescheme employed, the adjustment module 408 adjusts the read voltagethreshold to correct or compensate for the difference determined by thedirection module 406.

In a further embodiment, the adjustment module 408 determines an amountto adjust the read voltage threshold based on an amplitude of thedirection or amplitude of the difference determined by the directionmodule 406. In another embodiment, the adjustment module 408 may scaleor otherwise adjust the amplitude from the direction module 406 andadjust the read voltage threshold the adjusted amount. For example, theadjustment module 408, in one embodiment, may adjust the read voltagethreshold by several adjustment levels in a single adjustment, based onthe amplitude of the direction. In a further embodiment, the adjustmentmodule 408 may select an amount to adjust the read voltage thresholdbased on additional factors such as age, amount of wear, usage history,error history, or other aspects of the non-volatile memory media 110. Asdescribed above with regard to FIG. 3B, in certain embodiments, theadjustment module 408 may make a read voltage threshold adjustment basedon one or more statistics for the non-volatile memory device 102 thatthe configuration module 352 receives from the device factor module 354.

In another embodiment, the adjustment module 408 uses a search algorithmto determine the read voltage threshold based on the direction ofdeviation. For example, the range of voltages in the direction ofdeviation from the current read voltage threshold may be the searchspace for the search algorithm. The adjustment module 408, in oneembodiment, may use a linear search, a binary search, or the like todetermine the read voltage threshold. To check each step as part of thesearch algorithm, the data set read module 402 may re-read the data setin response to each adjustment, and the deviation module 404 mayre-determine whether the read bias of the re-read data set deviates fromthe known bias. The direction module 406 may re-determine a direction ofdeviation for the re-read data set to further the search. The adjustmentmodule 408 may iteratively readjust the read voltage threshold based onthe re-determined direction of deviation until the deviation module 404determines that the read bias of a re-read data set does not deviatefrom the known bias, or until each of the read voltage threshold levelhas been tested, and/or until the data set can be corrected using ECCcheckbits, or the like.

In one embodiment, the adjustment module 408 stops readjusting a readvoltage threshold once a retry threshold is satisfied. For example, ifthe ECC decoder 322 cannot correct a data error and/or if the read biasfor the data set continues to deviate from the known bias when a retrythreshold for the data set is satisfied, the adjustment module 408 maycease making adjustments to the read voltage threshold. The retrythreshold may be selected based on a set of possible read voltagethreshold levels, or the like. In one embodiment, a retry threshold setsa number of times which the adjustment module 408 may adjust a readvoltage threshold. In another embodiment, a retry threshold may set anamount of time in which the adjustment module 408 may make read voltagethreshold adjustments. The non-volatile memory controller 104, incertain embodiments, may take further remedial action in response to theretry threshold being satisfied, such as retiring the storage cellsassociated with the data set, logically replacing the storage cellsassociated with the data set, or the like.

In one embodiment, the adjustment module 408 does not adjust a readvoltage threshold, even if the deviation module 404 determines that theread bias of a data set deviates from the known bias, a data error hasoccurred, a retry threshold has not been met, or the like. Theadjustment module 408, in certain embodiments, may selectively adjust aread voltage threshold based on one or more risk factors associated withan adjustment to a grouping of storage cells. For example, risk factorsmay include an error rate for the grouping of storage cells (such as anUBER or the like), an erase cycle count for the grouping of storagecells, a storage request latency for the grouping of storage cells (suchas an average, maximum, or other storage request execution latency), anage of the grouping of storage cells, a number of previous adjustmentsto a read voltage threshold of the grouping of storage cells, and/orother potential risk factors. In one embodiment, the adjustment module408 may cancel or delay an adjustment to a read voltage threshold inresponse to one or more risk factors satisfying a risk threshold. In afurther embodiment, the non-volatile memory controller 104 may takefurther remedial action in response to one or more risk factorssatisfying a risk threshold.

The adjustment module 408, in one embodiment, adjusts the read voltagethreshold using a procedure or command provided by a manufacturer of thenon-volatile memory media 110. For example, in one embodiment, theadjustment module 408 may adjust the read voltage threshold by writing avalue to a settings register of the non-volatile memory media 110,sending a read voltage threshold parameter to the non-volatile memorymedia 110, or otherwise communicating an adjustment to a read voltagethreshold to the non-volatile memory media 110. The adjustment module408 may communicate the adjustment as an absolute value of a readvoltage threshold, an amount to adjust the read voltage threshold, orthe like. In a further embodiment, the non-volatile memory media 110provides a plurality of discrete levels (e.g., between 2 and 15different levels) to which the read voltage threshold may be adjusted.In other embodiments, the magnitude of a read voltage thresholdadjustment may be defined or recommended by a manufacturer or vendor ofthe non-volatile memory media 110.

The adjustment module 408, in one embodiment, adjusts the read voltagethreshold individually for a die, chip, PEB, or other discrete segmentof the non-volatile memory media 110. The adjustment module 408, in afurther embodiment, adjusts multiple read voltage thresholds for eachstorage cell. For example, in one embodiment, the storage cells of thenon-volatile memory media 110 are MLC storage cells, with multiple readvoltage thresholds per cell (e.g., a 2 bit MLC storage cell may havethree distinct read voltage thresholds). The adjustment module 408 maymove each of the multiple read voltage thresholds together or it maymove them independently.

In embodiments where the storage cells have multiple read voltagethresholds, each read voltage threshold is separated by a separationdistance. In one embodiment, the separation distances are uniformbetween each read voltage threshold. In a further embodiment, theadjustment module 408 adjusts the multiple read voltage thresholds witha single command or procedure and the separation distances between themultiple read voltage thresholds scale with the adjustment. For example,in one embodiment, the separation distances between read voltagethresholds may increase with larger read voltage thresholds and decreasewith lower read voltage thresholds. Scaling the separation distancesbetween read voltage thresholds upon adjustment, in one embodiment,provides a more even distribution of read voltage thresholds, so thatthe ranges of voltages at the ends of the ranges are not reduced orenlarged while middle ranges remain the same.

In one embodiment, the persistence module 410 stores a state of the readvoltage threshold. The persistence module 410, in one embodiment, ispart of the non-volatile memory controller 104. The persistence module410, in another embodiment, may send the read voltage threshold to thenon-volatile memory media 110 with each read operation. In a furtherembodiment, the persistence module 410 is part of the non-volatilememory media 110, causing the non-volatile memory media 110 to retainadjustments to the read voltage thresholds that the adjustment module408 makes. The persistence module 410, in one embodiment, storesmultiple read voltage thresholds, each read voltage threshold for adifferent segment or grouping of storage cells of the non-volatilememory media 110.

In one embodiment, a manufacturer of the non-volatile memory media 110provides a command or procedure to adjust a read voltage threshold for apredefined grouping of storage cells, such as a chip, physical eraseblock, physical page, or a die. In a further embodiment, the persistencemodule 410 stores read voltage thresholds for sub-groupings of storagecells that are smaller than the predefined groupings of storage cellsfor which the adjustment module 408 can make adjustments using themanufacturer provided command or procedure. The adjustment module 408may then, in another embodiment, readjust the read voltage thresholdwhen a data set is read from a sub-grouping based on the read voltagethresholds that the persistence module 410 stores. Examples ofsub-groupings may include PEBs, pages, ECC chunks/codewords, or otherphysical or logical divisions of a grouping of storage cells.

For example, in response to a read request for a data set from a firstsub-grouping of storage cells, the adjustment module 408 may adjust theread voltage threshold of the entire grouping of storage cells to alevel that the persistence module 410 stores for the first sub-grouping.In response to a read request for a data set from a second sub-grouping,in one embodiment, the adjustment module 408 may readjust the readvoltage threshold for the entire grouping to a level that thepersistence module 410 stores for the second sub-grouping. This allowsthe configuration module 352 to adjust the read voltage thresholds forthe non-volatile memory media 110 at a finer scope than may be providedfor in commands or procedures available for the non-volatile memorymedia 110. For example, a manufacturer may provide a command, procedure,or methodology for adjusting a read voltage threshold for a die, chip,or other grouping of storage cells and the adjustment module 408 mayadjust read voltage thresholds for individual PEBs or othersub-groupings in accordance with that command procedure or methodology.

In one embodiment, the configuration module 352 processes the data setin response to an uncorrectable (meaning herein uncorrectable by the ECCdecoder 322, as discussed herein a correction may be possible after anadjustment of the read voltage threshold) data error, as describedabove, and adjusts the read voltage threshold one or more times untilthe data error is no longer uncorrectable and can be repaired using ECCcheckbits for the data set. In one embodiment, the ECC module 412cooperates with the ECC decoder 322 to determine whether or not the ECCdecoder 322 can correct an error in the data set. Alternatively, theconfiguration module 352 cooperates with the ECC decoder 322 todetermine whether or not the ECC decoder 322 can correct an error in thedata set.

The configuration module 352, in one embodiment, repeats the processingsteps described above until the ECC module 412 determines that the ECCdecoder 322 can correct the error. For example, in a further embodiment,the data set read module 402, the deviation module 404, the directionmodule 406, and the adjustment module 408 may repeatedly read the dataset, determine that the read bias for the data set deviates from theknown bias, determine the direction of deviation for the data set, andadjust the read voltage threshold as described above until the ECCmodule 412 determines that the ECC decoder 322 can correct the error.

As described in greater detail with regard to FIGS. 6A and 6B, in oneembodiment, a data set may be stored across several die, chips,channels, storage elements, PEBs, or other grouping of storage cells.ECC checkbits, in one embodiment, may be calculated and storedindependently for each grouping of storage cells. In another embodiment,the ECC checkbits, stored together with each grouping of storage cells,for example as part of an ECC chunk/codeword.

In a further embodiment, the ECC module 412 uses ECC checkbits todetermine in which die, chip, channel, storage element, PEB, or othergrouping of storage cells of the non-volatile memory media 110 anuncorrectable error has occurred. The ECC module 412, in one embodiment,verifies data sets of each grouping of storage cells using ECC checkbitsto determine which particular grouping from a set of groupings ofstorage cells have uncorrectable errors. The configuration module 352,in one embodiment, adjusts one or more read voltage thresholds in theparticular groupings of storage cells with an uncorrectable error.

In one embodiment, the distribution module 414 determines that the readbias of the data set is within an expected distribution of the knownbias, and that no additional adjustments of the read voltage thresholdshould be made. In a further embodiment, the data set read module 402,the deviation module 404, the direction module 406, and the adjustmentmodule 408 continue to re-read the data set with a new read voltagethreshold, re-determine that the read bias for the data set deviatesfrom the known bias, re-determine the direction of deviation for thedata set, and readjust the read voltage threshold until the distributionmodule 414 determines that the read bias of the data set is within theexpected distribution.

The distribution module 414, in one embodiment, may cooperate with or beintegrated with the deviation module 404. In one embodiment, theconfiguration module 352 uses either the ECC module 412 or thedistribution module 414 to determine when adjustment of the read voltagethreshold should be made or is complete. In a further embodiment, thedistribution module 414 compares read biases of data sets from severaldie, chips, channels, storage elements, PEBs, or other grouping ofstorage cells of the non-volatile memory media 110 to the distributionof the known bias to determine in which grouping of storage cells anerror has occurred, and the configuration module 352 adjusts one or moreread voltage thresholds in a grouping of storage cells with an error.

In one embodiment, the ECC module 412 and/or the distribution module 414cooperate with the data set source module 422. The data set sourcemodule 422, in one embodiment, determines from which specific groupingof storage cells the data set was read. For example, the data set sourcemodule 422 may determine which die, chip, channel, storage element, PEB,or other grouping of storage cells is the source of the data set. In oneembodiment, the data set source module 422 determines from whichspecific grouping of storage cells the data was read in response to thedeviation module 404, the ECC module 412, and/or the distribution module414 determining that the data set has a read bias that deviates from aknown bias, has a data error, or the like.

In one embodiment, the data set source module 422 determines from whichspecific grouping of storage cells the data set was read based on aposition of the data set within a sequence of data sets. For example, inone embodiment, the non-volatile memory media 110 may comprise aplurality of groupings of storage cells, and each grouping of storagecells may be read in parallel during a read operation. The data setsource module 422, in one embodiment, may use known information abouthow the write data pipeline 106 and/or the read data pipeline 108processes data, and known information about the plurality of groupingsof storage cells, to determine from which grouping of storage cells thedata set was read.

For example, in one embodiment the write data pipeline 106 and the readdata pipeline 108 may each have a 64 bit (8 byte) data path, thenon-volatile memory media 110 may comprise a 24 die wide array, and 8bytes may be read in parallel from each of the 24 die during a readoperation, for a total of 192 bytes per read operation. Based on thisinformation, the data set source module 422, in one embodiment, candetermine from which die or other grouping of storage cells, a data setwas read based on the position of an 8 byte data set within the 192bytes.

The data set source module 422, in a further embodiment, may count orotherwise track the number of data sets processed as part of a readoperation to determine the position of the data set in the sequence ofdata sets. For example, 8 bytes may be read in sequence from the 24 diestarting with a first die, thus if the ECC module 412 and/or thedistribution module 414 detects a read bias deviation or a data errorduring operations on the fifth 8 byte set of data, the data set sourcemodule 422 identifies that this 8 byte set of data came from the fifthdie of the 24 die.

By using the position of the data set in a sequence of data sets andother known information, the data set source module 422, in oneembodiment, can determine the grouping of storage cells from which thedata set was read without using an identifier or other externalinformation. Identifying the die, chip, channel, PEB, or other groupingof storage cells that exhibit the read bias difference permits promptremedial actions to be taken such as changing the read voltagethreshold, logical swapping of the grouping of storage cells with areserved grouping, and other forms of remedial action.

In one embodiment, the proactive configuration module 424 manages thenon-volatile memory media 110 by proactively setting and adjustingconfiguration parameters for storage cells of the non-volatile memorymedia 110. By determining configuration parameters proactively before anerror occurs, the proactive configuration module 424 may prevent certainerrors from occurring, without the performance penalty of retrying readsor performing other remedial measures for the prevented errors. Theproactive configuration module 424, in certain embodiments, optimizesconfiguration parameters for a use case of the non-volatile memorydevice 102 to optimize storage cells for the use case instead of usingdefault parameters.

As described above, a configuration parameter is a parameter of a set ofstorage cells that is modifiable by way of an interface, such as a readthreshold, a write or program threshold, an erase threshold, or thelike. An interface for modifying a configuration parameter may include aprogrammable data register, a command interface of a control bus for thenon-volatile memory media 110, an API of a device driver of thenon-volatile memory device 102, a control parameter for the non-volatilememory controller 104, or the like.

The proactive configuration module 424 references one or more mediacharacteristics for a set of storage cells to determine a configurationparameter for the set of storage cells. A media characteristic is astatistic, heuristic, mathematical model, transform, or other descriptorassociated with an attribute of the non-volatile memory media 110. Amedia characteristic for a set of storage cells may be substantiallystatic or may be dynamic and change over time.

A media characteristic, in one embodiment, includes or relates to amake, a model, a manufacturer, a product version, or the like for thenon-volatile memory device 102 and/or for the non-volatile memory media110. In another embodiment, a media characteristic describes anattribute or statistic for a set of particular storage cells, such as aprogram/erase cycle count for the set of storage cells, a read count forthe set of storage cells, a retention time since a previous write forthe set of storage cells, a dwell time for the set of storage cells suchas a logical or physical erase block (e.g., a time between a program ofan erase block and an erase of the erase block), an average of multipleprevious dwell times for the set of storage cells, an error statisticfor the set of storage cells, or the like. A media characteristic, in afurther embodiment, may include or relate to an environmental conditionor a use of the non-volatile memory device 102 and/or of thenon-volatile memory media 110, such as a temperature, a use case (e.g.,a cache use case, an archival use case, a server use case, an enterpriseuse case, a consumer use case, etc.), or the like.

The proactive configuration module 424, in response to determining aconfiguration parameter for a set of storage cells, configures the setof storage cells to use the determined configuration parameter. Theproactive configuration module 424 may periodically update mediacharacteristics for a set of storage cells, update a configurationparameter for the set of storage cells, and reconfigure the set ofstorage cells to use the updated configuration parameter. The proactiveconfiguration module 424 may configure storage cells with configurationparameters during execution of input/output operations, during a startupoperation, in response to a background scan of a set of storage cellsindicating a changed media characteristic, or the like.

In order to reduce the overhead associated with tracking configurationparameters for each storage cell, each page, each erase block, or thelike, in one embodiment, the proactive configuration module 424 managesconfiguration parameters in groups or sets. For example, the proactiveconfiguration module 424 may determine and manage configurationparameters for groups or sets of pages, physical erase blocks, logicalerase blocks, wordlines, ECC chunks/codewords, chips, die, planes in adie, or other storage regions. The proactive configuration module 424may group pages or other storage regions that have similar mediacharacteristics, such as similar error rates (e.g., RBER, UBER), similarages, similar program/erase counts, similar physical media locations,similar locations in a programming order, similar architectures, or thelike, and determine different configuration parameter settings for thedifferent groups. For example, the proactive configuration module 424,in certain embodiments, may group upper pages (e.g., MSB pages), lowerpages (e.g., LSB pages), subsets of upper and/or lower pages, a set ofthe first N pages in a page programming order, a set of the middle Npages in a page programming order, a set of the last N pages in a pageprogramming order, and/or other subsets of pages or other storageregions, and may manage configuration parameter settings by group orset.

In certain embodiments, the proactive configuration module 424configures storage cells independently of the adjustments describedabove with regard to the adjustment module 408. For example, theproactive configuration module 424 may be separate from theconfiguration module 352, the proactive configuration module 424 may bepart of a storage controller 104 without a configuration module 352, orthe like. In other embodiments, the adjustment module 408 and theproactive configuration module 424 may cooperate. For example, theadjustment module 408 may make closed loop feedback based adjustments toone or more configuration parameters that the proactive configurationmodule 424 has set using an open loop model, or the like.

In one embodiment, the write voltage module 416 sets a write voltagelevel for writing data to the storage cells of the non-volatile memorymedia 110. The write voltage level is a programming voltage thatspecifies the minimum or maximum voltage used to program or change astate of a storage cell, a step magnitude for an incremental step pulseprogramming operation, a maximum number of iterations for an incrementalstep pulse programming operation, a program verify threshold for aprogram operation, an initial bias for an incremental step pulseprogramming operation, or the like. In one embodiment, the write voltagemodule 416 may be integrated with the configuration module 352 and/orthe proactive configuration module 424.

For example, for NAND flash non-volatile memory, the write voltageand/or other program related configuration parameters, changes the stateof a storage cell from a binary one to a binary zero. The write voltagemodule 416, in one embodiment, writes known patterns to the storagecells, then reads the pattern back determining the read voltagethreshold, and adjusts the write threshold until the desired readthreshold is met. The write voltage module 416, in a further embodiment,adjusts the write voltage level based on a mathematical model thatspecifies write voltage level values based on endurance and dataretention requirements of a storage cell relative to an age of thestorage cell. In one embodiment, the age of the storage cell is computedin terms of program and erase cycles. The write voltage module 416, inone embodiment, performs a test write to one or more storage cells,detects the read voltage of at least one of the storage cells, andadjusts the write voltage level until the read voltage meets a thresholdvalue. The write voltage module 416, in a further embodiment, performsthe test write by writing a data set with a known bias to the storagecells, and tests the read voltage by determining if a read bias of theread data set deviates from the known bias.

The write voltage module 416, in one embodiment, may begin with aminimum write voltage, and increase the write voltage until the readvoltage meets a threshold value. In a further embodiment, the writevoltage module 416 may begin with a maximum write voltage, and decreasethe write voltage until the read voltage meets a threshold value. Thewrite voltage module 416, in one embodiment, may select a write voltagelevel that balances the time to program the storage cells with a desiredendurance and/or data retention for the storage cells.

Proactive Configuration

FIG. 5 depicts one embodiment of the proactive configuration module 424.The proactive configuration module 424, in certain embodiments, may besubstantially similar to the proactive configuration module 424described above with regard to FIG. 4. In the depicted embodiment, theproactive configuration module 424 includes a media characteristicmodule 502, a configuration parameter module 504, a cell configurationmodule 506, a characteristic update module 508, a configuration updatemodule 510, an adaptive configuration module 512, an adjustmentthreshold module 514, a sparse adjustment module 516, and a backstopmodule 518. At least a portion of the media characteristic module 502,the configuration parameter module 504, the cell configuration module506, the characteristic update module 508, the configuration updatemodule 510, the adaptive configuration module 512, the adjustmentthreshold module 514, the sparse adjustment module 516, and the backstopmodule 518 may be part of a device driver installed on the computer 112or another host device for the non-volatile memory device 102 and/orpart of hardware for the non-volatile memory device 102, such asfirmware of an FPGA, an ASIC, or the like.

In one embodiment, the media characteristic module 502 references orotherwise determines one or more media characteristics for a set ofstorage cells of the non-volatile memory media 110, for abodes orstorage states of a set of storage cells of the non-volatile memorymedia 110, or the like. The set of storage cells may comprise a singlestorage region, such as a physical page, a logical page, a physicalerase block, a logical erase block, a wordline, an ECC chunk/codeword, achip, a die, a plane in a die, or the like, or may comprise a set ofmultiple storage regions. In certain embodiments, different storagestates, abodes, encoding digits (e.g., LSB, MSB) of the storage cells ofthe non-volatile memory media 110, as described in greater detail belowwith regard to FIGS. 6C and 6D, may have different mediacharacteristics, and the media characteristic module 502 may monitor orotherwise determine the different media characteristics separately fordifferent abodes/storage states, or the like.

The media characteristic module 502 may determine one or more mediacharacteristics itself, may receive media characteristics from anothermodule, may retrieve media characteristics from a media characteristicrepository, or the like. As described above, a media characteristic is astatistic, heuristic, or other descriptor associated with an attributeof the non-volatile memory media 110. Media characteristics may includeand/or relate to a make, a model, a manufacturer, a product version, orthe like for the non-volatile memory device 102 and/or for thenon-volatile memory media 110; an attribute or statistic for a set ofstorage cells; an environmental condition or a use case of thenon-volatile memory device 102 and/or of the non-volatile memory media110; and/or another statistic, heuristic, or other descriptor for anattribute of the non-volatile memory media 110.

A media characteristic for a set of storage cells affects or informs thedetermination of a configuration parameter for the set of storage cells.In one embodiment, the media characteristics include a program/erasecycle count for a set of storage cells. In another embodiment, the mediacharacteristics include a read count for a set of storage cells. Themedia characteristics, in a further embodiment, include a retention timesince a previous write for a set of storage cells. In an additionalembodiment, the media characteristics include a temperature for a set ofstorage cells. The media characteristics, in certain embodiments,include a use case for a set of storage cells. In another embodiment,the media characteristics include an error statistic for a set ofstorage cells, such as an UBER, a RBER, or the like. In a furtherembodiment, the media characteristic may include previous or historicalconfiguration parameters for a set of storage cells, configurationparameters or media characteristics for other sets of storage cells, orthe like.

The media characteristic module 502, in certain embodiments, manages thecollection of and/or maintenance of media characteristics. The mediacharacteristic module 502 may maintain media characteristics in and/orretrieve media characteristics from a media characteristic repository.One example of a media characteristic repository is described in greaterdetail below with regard to FIGS. 7A and 7B. The media characteristicmodule 502, in certain embodiments, references, determines, and/ormanages media characteristics for several different sets of storagecells, such as each storage region or storage division of thenon-volatile memory device 102. A media region may include an eraseblock (logical or physical), a page (logical or physical), an ECCchunk/codeword, a division within a page, a set of pages, a die, a planein a die, a chip, or the like.

In one embodiment, the media characteristic module 502 may be similarto, may work with, and/or may be integrated with the device factormodule 354 described above with regard to FIG. 3B. For example, themedia characteristics may include one or more of the statisticsdescribed above with regard to the device factor module 354, such as atemperature for the non-volatile memory device 102, an error rate forthe non-volatile memory device 102 (such as an UBER, RBER, or the like),a program/erase cycle count for the non-volatile memory device 102, astorage request latency for the non-volatile memory device 102 (such asan average, maximum, or other storage request execution latency), an ageof the non-volatile memory device 102, and/or other statistics orcharacteristics. The media characteristic module 502, in certainembodiments, may receive input, directly or indirectly, from the one ormore sensors 356, from other modules or elements such as the ECC decoder322, or the like.

In one embodiment, the configuration parameter module 504 determines aconfiguration parameter for a set of storage cells based on one or moremedia characteristics from the media characteristic module 502 for theset of storage cells. The set of storage cells for which theconfiguration parameter module 504 determines the configurationparameter may include an erase block (logical or physical), a page(logical or physical), an ECC chunk/codeword, a division within a page,a set of pages, a die, a plane in a die, a chip, or the like. Theconfiguration parameter module 504 may determine different configurationparameters for different sets of storage cells, different sets of pages,different abodes/storage states of storage cells, or the like, based onthe corresponding media characteristics. The configuration parametermodule 504, in certain embodiments, determines configuration parametersdynamically during operation or runtime of the non-volatile memorydevice 102, as adjustments or updates to initial or default settings.

As described above, a configuration parameter is a parameter of a set ofstorage cells that is modifiable by way of an interface. Configurationparameters may relate to writing to or programming storage cells,reading from storage cells, erasing storage cells, and/or to anotherparameter for storage cells. The configuration parameter module 504 maydetermine a configuration parameter as an absolute data value, as anoffset or adjustment to a data value, or as another parameter with whichthe cell configuration module 506 can configure a set of storage cells,as described below.

One embodiment of a configuration parameter for reading from storagecells is a read threshold such as a read voltage threshold, aresistivity threshold, or the like. Other embodiments of configurationparameters for reading from storage cells may include whether to performa read retry in response to an error, whether to adjust a read thresholdor other configuration parameter prior to a read retry, or the like. Forexample, the configuration parameter module 504 may determine a numberof read retries to perform, a maximum number of read retries,configuration parameters for each read retry, or the like based ondiscovered or monitored media characteristics, media characteristicsfrom a vendor or manufacturer, or the like.

Various embodiments of configuration parameters for writing/programmingstorage cells include a step magnitude for an incremental step pulseprogramming operation, a maximum number of iterations for an incrementalstep pulse programming operation, a program verify threshold for aprogram operation, an initial bias for an incremental step pulseprogramming operation, a duration for an incremental step pulseprogramming operation, or the like. A configuration parameter forerasing storage cells, in certain embodiments, may include a stepmagnitude for an incremental step pulse erase operation, a maximumnumber of iterations for an incremental step pulse erase operation, anerase verify threshold for an erase operation, an initial bias for anincremental step pulse erase operation, a duration for an incrementalstep pulse programming operation, or the like. One of skill in the art,in light of this specification, will recognize other configurationparameters for storage cells that may be modifiable by way of aninterface.

A configuration parameter for managing, reading from,writing/programming to, and/or erasing storage cells, as describedabove, may generally be referred to as a storage threshold for thestorage cells. For example, a storage threshold, in various embodiments,may include a read voltage threshold, a resistivity threshold, a numberof read retries to perform, a maximum number of read retries, a stepmagnitude for an incremental step pulse programming operation, a maximumnumber of iterations for an incremental step pulse programmingoperation, a program verify threshold for a program operation, aninitial bias for an incremental step pulse programming operation, aduration for an incremental step pulse programming operation, a stepmagnitude for an incremental step pulse erase operation, a maximumnumber of iterations for an incremental step pulse erase operation, anerase verify threshold for an erase operation, an initial bias for anincremental step pulse erase operation, a duration for an incrementalstep pulse programming operation, or another storage threshold.

The configuration parameter module 504 may base a configurationparameter on one or more media characteristics by entering the one ormore media characteristics into an equation, into a mathematical model,into a lookup table (“LUT”), into a matrix, or the like; by performing apredefined transform or operation on the one or more mediacharacteristics; or by otherwise referencing and/or manipulating the oneor more media characteristics to determine the configuration parameter.A configuration parameter equation, mathematical model, LUT, matrix, orthe like may be based on empirical data, such as test data, historicaldata, and the like. A design engineer or the like, in one embodiment,may test sets of storage cells with various media characteristics, suchas non-volatile memory media from various manufacturers or the like, anddetermine optimal configuration parameters for storage cells with thevarious media characteristics. For example, an equation, mathematicalmodel, LUT, matrix, or the like may indicate that non-volatile memorymedia 110 from manufacturer X tends to have Y amount of natural drift incell values after 1,000 program/erase cycles such that a read thresholdcan be increased by Z volts to compensate, or the like.

In other embodiments, the configuration parameter module 504 maydynamically determine a configuration parameter; an equation,mathematical model, LUT, matrix, transform, or the like to define aconfiguration parameter; an adjustment to a configuration parameter; orthe like during operation of the non-volatile memory device 102, asdescribed above with regard to the adjustment module 408. For example,the configuration parameter module 504 may determine configurationparameters for various media characteristics initially based on trialand error, based on a direction from the direction module 406, or thelike and may autonomously correlate the effectiveness of theconfiguration parameter, based on a change in an error rate such asRBER, UBER, or the like, to determine an equation, mathematical model,LUT, matrix, transform, or the like for determining subsequentconfiguration parameters and/or configuration parameter adjustments.

In one embodiment, the media characteristics for a set of storage cellsinclude a temperature. A temperature for a set of storage cells mayaffect the speed of the effects of one or more other mediacharacteristics on the set of storage cells. For example at highertemperatures, the rate of change for media characteristics relating toerror statistic such as Raw Bit Error Rates (RBER) and data retentiontimes may increase and certain adjustments to configuration parametersmay mitigate the effect. In certain embodiments, the configurationparameter module 504 may adjust or scale a configuration parameter, amedia characteristic, or the like by a temperature to compensate for theeffects of temperature, normalizing the data for temperature. Thetemperature for a set of storage cells may be an average temperature, atemperature over a sliding window, a current temperature, a temperaturefor the non-volatile memory device 102, or another temperaturemeasurement associated with one or more sets of storage cells.

The one or more media characteristics, in one embodiment, indicate tothe configuration parameter module 504 a trend, an optimization, or thelike for a configuration parameter and the configuration parametermodule 504 determines a configuration parameter to satisfy the trend oroptimization. For example, a magnitude of a program/erase cycle count, aread count, a UBER, a RBER, or another media characteristic may indicatean amount that a read voltage or other configuration parameter hasdrifted, and the configuration parameter module 504 may proactivelydetermine a read voltage threshold or other configuration parameterbased on the media characteristic, without direct feedback from thestorage cells, such as a read, a read retry, or the like.

In one embodiment, the configuration parameter module 504 maintainsconfiguration parameters for sets of storage cells of different storageregions or storage divisions of the non-volatile memory media 110, suchas an erase block (logical or physical), a page (logical or physical),an ECC chunk/codeword, a division within a page, a set of pages, anabode/storage state, a die, a plane in a die, a chip, or the like, in aconfiguration parameter repository. One example of a configurationparameter repository is described in greater detail below with regard toFIGS. 8A and 8B. By determining and managing separate mediacharacteristics and/or configuration parameters for different storageregions, for different abodes/storage states, or the like, the proactiveconfiguration module 424, in certain embodiments, may customizeconfiguration parameters for each storage region or abode/storage stateindividually, thereby reducing errors, extending the lifetime of thenon-volatile memory media 110, or the like.

Different abodes/storage states of storage cells may have differentmedia characteristics. For example, certain abodes/storage states, suchas the L0 state described below with regard to FIG. 6C, may be moreprone to program, read, or other disturbances. An abode or storagestate, as used herein, is the range of read levels, such as a readvoltage level for flash media, a read resistivity level for PCM media,or the like, associated with a particular set of data values. Readthresholds, such as a read voltage threshold, a read resistivitythreshold, or the like, may separate abodes or storage states. Oneexample of abodes or storage states is described below with regard toFIGS. 6C and 6D, where abode L0 corresponds to data values 11, L1corresponds to 01, L2 corresponds to 00, and L3 corresponds to 10 andabodes L0, L1, L2, and L3 are divided by read voltage thresholds 662 a-cin FIG. 6C and by adjusted read voltage thresholds 664 a-c in FIG. 6D.

For a given storage cell or set of storage cells, in one embodiment, theconfiguration parameter module 504 may determine and manage multipleconfiguration parameters. In certain embodiments, the configurationparameter module 504 may individually determine and manage differentsettings or adjustments for configuration parameters for each storagestate or abode of storage cells of the non-volatile memory media 110.For example, the configuration parameter module 504 may determinedifferent read voltage threshold settings for abodes/storage states L0,L1, L2, and L3 as described below with regard to FIGS. 6C and 6D, maydetermine different settings or adjustments for read level R1, readlevel R2, and read level R3 for storage cells as described below withregard to FIGS. 8A and 8B, may determine an incremental step pulseprogramming parameter for a programming operation as described above,may determine an incremental step pulse erase parameter for an eraseoperation as described above, or the like. In this manner, theconfiguration parameter module 504 may optimize configuration parametersettings individually for different abodes/storage states.

In certain embodiments, to reduce the overhead of tracking mediacharacteristics and/or configuration parameters at a fine grain, such asfor each storage cell, each page, each erase block, or the like, theconfiguration parameter module 504 may determine, select, or otherwisemanage configuration parameters in groups or sets. For example, theconfiguration parameter module 504 may determine and manageconfiguration parameters for groups or sets of pages, physical eraseblocks, logical erase blocks, wordlines, ECC chunks/codewords, chips,die, planes in a die, or other storage regions. The configurationparameter module 504 may group pages or other storage regions that havesimilar media characteristics, such as similar error rates (e.g., RBER,UBER), similar ages, similar program/erase counts, similar physicalmedia locations, similar architectures, or the like, and determinedifferent configuration parameter settings for the different groups orsets.

For example, in one embodiment, even and odd pages may have differenterror rates, such as RBERs, UBERs, or the like, and the configurationparameter module 504 may determine a first configuration parameter for aset of even pages and a second configuration parameter for a set of oddpages. In another embodiment, upper and lower pages of multi-levelstorage cells may have different error rates, such as RBERs, UBERs, orthe like, and the configuration parameter module 504 may determine afirst configuration parameter for a set of lower pages and a secondconfiguration parameter for a set of upper pages. In a furtherembodiment, one or more pages toward a first end of the upper pages andone or more pages toward a second end of the upper pages may have highererror rates, such as RBERs, UBERs, or the like, than the other upperpages, and the configuration parameter module 504 may determine a thirdconfiguration parameter for a set including the one or more pages towardthe first end and the one or more pages toward the second end.

In general, pages or storage regions may be divided into groups or setswith similar media characteristics, such as error rates, ages,program/erase counts, physical media locations, architectures, or thelike, and the configuration parameter module 504 may determine differentconfiguration parameters for the different groups or sets. Theconfiguration parameter module 504, in certain embodiments, may base aconfiguration parameter for a set of pages or other storage regions onan average media characteristic for the set, such as a mean, median,mode, or the like. Examples of sets of pages grouped by error rate aredescribed below with regard to FIGS. 6E, 6F, and 6G. Even when managingor determining configuration parameters by sets, groups, or storageregions, in certain embodiments, the configuration parameter module 504may also determine different configuration parameters for differentabodes/storage states of the storage cells within the sets, groups, orstorage regions.

For example, the configuration parameter module 504 may determinesettings for the R1, R2, and R3 read voltage thresholds for a first setof pages and may determine different settings for the R1, R2, and R3read voltage thresholds for a second set of pages, as described belowwith regard to FIG. 8B. In one embodiment, storage cells may be in morethan one set of pages, such as a set of upper pages and a set of lowerpages or the like, and the configuration parameter module 504 maydetermine different configuration parameters for the same storage cellsdepending on which page is being accessed or used. While the three readvoltage thresholds R1, R2, R3 of FIG. 8 are provided as one exampleembodiment, in other embodiments, storage cells may have differentnumbers of storage states/abodes, read voltage thresholds, or otherconfiguration parameters. For example, in one embodiment, certain 20 nmnon-volatile memory media 110 may have ten different read voltagethresholds R1-R10, set using different registers or the like, and theconfiguration parameter module 504 may determine different values forR1-R10 for different sets, groups, storage regions, and/or differentabodes/storage states.

In certain embodiments, the configuration parameter module 504 maydetermine a configuration parameter for one set of storage cells basedon another target set of storage cells. The target set of storage cellsmay have known and/or controlled use characteristics (e.g., mediacharacteristics or the like) that the configuration parameter module 504uses to determine a configuration parameter for another set of storagecells. In particular, the configuration parameter module 504 may comparemedia characteristics of the target set of storage cells to mediacharacteristics of a set of storage cells presently being configured.Such a comparison can be used to further optimize the determinedconfiguration parameter for the set of storage cells. The target set ofstorage cells may store known data, such as metadata, system data, aknown pattern of data, or the like, and the configuration parametermodule 504 may determine a configuration parameter for another set ofdata based on the known data.

In another embodiment, the configuration parameter module 504 determinesa configuration parameter for a set of storage cells based on adetermined configuration parameter for a target set of storage cells,based on one or more media characteristics for a target set of storagecells, or the like. For example, the configuration parameter module 504may use a configuration parameter for a target set of storage cells as aconfiguration parameter for another set of storage cells, may adjust aconfiguration parameter of a target set of storage cells for use indetermining the configuration parameter for another set of storagecells, may use media characteristics for a target set of storage cellsto determine a configuration parameter for another set of storage cells,or the like. In this manner, the target set of storage cells serves as acontrol group for use in managing other sets of storage cells. Thetarget set of storage cells may be used in certain embodiments in amanner analogous to how “system tracks” have been used in hard diskdrive technologies to make modifications to configuration parametersover the life of the storage device 102. In a further embodiment, theconfiguration parameter module 504 compares one or more mediacharacteristics for a set of storage cells to one or more mediacharacteristics for a target set of storage cells and determines aconfiguration parameter for the set of storage cells based on adifference between the media characteristics.

The configuration parameter module 504, in certain embodiments, bases aconfiguration parameter for a set of storage cells on a target set ofstorage cells to bootstrap the configuration parameter in response to alack of known media characteristics for the set of storage cells. Theconfiguration parameter module 504 may bootstrap a configurationparameter for a set of storage cells during a startup operation oranother operation where media characteristics for the set of storagecells may not yet be available, but media characteristics or other datamay be available for a target set of storage cells. For example,metadata stored in a metadata region of the non-volatile memory media110 may have a known or controlled program/erase count and theconfiguration parameter module 504 may base a configuration parameterfor a region of the non-volatile memory media 110 storing user data onthe known or controlled program/erase count for the metadata region.

In one embodiment, the cell configuration module 506 configures a set ofstorage cells to use a configuration parameter that the configurationparameter module 504 determines for the set of storage cells. Asdescribed above, a set of storage cells may include groups or sets ofpages, physical erase blocks, logical erase blocks, wordlines, ECCchunks/codewords, chips, die, planes in a die, or other storage regionsincluding one or more storage cells. The storage cell configurationmodule 506 may configure different sets of storage cells, different setsof pages, different storage states or abodes of storage cells, or thelike to use different configuration parameters, as determined by theconfiguration parameter module 504. The cell configuration module 506,in one embodiment, configures storage cells to use a configurationparameter such that the configuration parameter is used for subsequentaccesses to and/or operations on the storage cells.

The cell configuration module 506 uses an interface of a set of storagecells to configure the set of storage cells. The interface may comprisea publicly known interface or a proprietary interface. The configurationmodule 506 may configure a set of storage cells by setting a dataregister, by sending a command over a command interface of a control busfor the non-volatile memory media 110, by calling an API of a devicedriver of the non-volatile memory device 102, by setting a controlparameter for the non-volatile memory controller 104, or otherwiseconfiguring the set of storage cells. The cell configuration module 506may use particular command instructions, a particular sequence ofcommand instructions, and/or use particular parameters, registersettings, or other differences from regular commands (general purposecommands) used to interface with the set of storage cells. The cellconfiguration module 506 may receive configuration parameters from theconfiguration parameter module 504, may retrieve configurationparameters from a configuration parameter repository, or the like.

The cell configuration module 506, in one embodiment, configures a setof storage cells to use a determined configuration parameter in responseto a trigger. The trigger, in certain embodiments, is selected based onan architecture of the non-volatile memory device 102 and/or of thenon-volatile memory media 110. For example, certain non-volatile memorydevices 102 and/or non-volatile memory media 110 may retain aconfiguration parameter across multiple input/output operations, whileanother non-volatile memory device 102 and/or non-volatile memory media110 may require a configuration parameter to be set with eachinput/output operation, or the like. The cell configuration module 506may configure a set of storage cells once during initialization of thenon-volatile memory media 110, dynamically with each command issued tothe set of storage cells, during operation of the non-volatile memorymedia 110 in response to events or time intervals, in response toanother trigger, or the like.

In one embodiment, a trigger for the cell configuration module 506includes a change in a media characteristic for a set of storage cells,a change of a predefined magnitude in a media characteristic for the setof storage cells, or the like, and the cell configuration module 506configures the set of storage cells in response to a change in the mediacharacteristics. In another embodiment, a trigger for the cellconfiguration module 506 includes an input/output request for a set ofstorage cells, such as a read request, a write request, an eraserequest, or the like. For example, in certain embodiments, the cellconfiguration module 506 may configure a set of storage cells to use aread configuration parameter in response to a read request for thestorage cells, may configure a set of storage cells to use a writeconfiguration parameter in response to a write request for the storagecells, may configure a set of storage cells to use an eraseconfiguration parameter in response to an erase request, or the like.

In a further embodiment, a startup operation for the non-volatile memorydevice 102, a regular shutdown operation for the non-volatile memorydevice 102, or the like is a trigger for the cell configuration module506 to configure one or more sets of storage cells. In certainembodiments, once the cell configuration module 506 configures a set ofstorage cells with a configuration parameter in response to a startupoperation, the set of storage cells retain the configuration parameteruntil a shutdown operation and a subsequent startup operation, or thelike. How a set of storage cells retain configuration parameters mayvary depending on the type of configuration parameter, the architectureof the set of storage cells, and the like.

The cell configuration module 506, in a further embodiment, mayconfigure only a subset of one or more abodes/storage states of a set ofstorage cells to use a configuration parameter. For example, if aconfiguration parameter setting for an abode/storage state has little orno change from a previous configuration parameter setting, from adefault configuration parameter setting, or the like, the cellconfiguration module 506 may configure one or more other abodes/storagestates without configuring the abode/storage state with little or nochange in the configuration parameter setting. In certain embodiments,configuration settings for different abodes/storage states of a set ofstorage cells may be set by writing the settings to different registersassociated with the different abodes/storage states, and the cellconfiguration module 506 may write configuration settings, such as readvoltage thresholds or the like, only to registers for which theconfiguration settings have changed. In other embodiments, the cellconfiguration module 506 may set configuration settings for eachabode/storage state of a set of storage cells in response to eachstorage request or other trigger event.

The cell configuration module 506 may configure storage cells a storageregion at a time, writing configuration parameter settings to registersfor a group or set of pages, a physical erase block, a logical eraseblock, a wordline, an ECC chunk/codeword, a chip, a die, a plane in adie, or another storage region. In certain embodiments, the cellconfiguration module 506 may configure storage cells by storingconfiguration parameter settings in a bank cache such as a buffer 222 orthe like for the non-volatile memory media 110. In a further embodiment,the cell configuration module 506 may configure storage cells using aconfiguration parameter override table or other override metadataconfigured, scaled, or otherwise structured according to an architectureof the non-volatile memory media 110.

In one embodiment, the characteristic update module 508 updates one ormore media characteristics for a set of storage cells in response to anupdate event for the set of storage cells. An update event is a trigger,in response to which, the characteristic update module 508 updates mediacharacteristics. Certain media characteristics, such as a make, a model,a manufacturer, a product version, or the like of the non-volatilememory device 102 and/or the non-volatile memory media 110 may besubstantially static, and the characteristic update module 508, incertain embodiments, may not update such media characteristics, mayupdate such media characteristics less frequently, or the like. Othermedia characteristics, such as a program/erase cycle counts, readcounts, retention times, temperatures, use cases, error statistics, andthe like may be dynamic and change frequently.

In one embodiment, a background scan of the non-volatile memory media110 may be an update event. For example, the characteristic updatemodule 508 may perform a background scan of the non-volatile memorymedia 110 and update records of media characteristics for sets ofstorage cells in response to scanning the sets of storage cells duringthe background scan. A background scan, in certain embodiments, may beinformed by or optimized based on media characteristics of thenon-volatile memory media, may be configured to determine mediacharacteristics per abode/storage state, or the like.

In another embodiment, an input/output request for the set of storagecells or for a neighboring set of storage cells, such as a read request,a write request, an erase request, or the like, is an update event andthe characteristic update module 508 updates media characteristics for aset of storage cells in response to the input/output request. An updateevent for the characteristic update module 508, in a further embodiment,may include a startup operation and/or shutdown operation for thenon-volatile memory device 102. In certain embodiments, a garbagecollection operation for a set of storage cells is an update event. Forexample, the characteristic update module 508 may update mediacharacteristics for a set of storage cells as a garbage collectionoperation recovers storage capacity of the set of storage cells, or thelike.

The characteristic update module 508, in one embodiment, updates mediacharacteristics in cooperation with the media characteristic module 502,using the media characteristic module 502, or the like. In certainembodiments, the characteristic update module 508 may update mediacharacteristics stored in a media characteristic repository, asdescribed in greater detail below with regard to FIGS. 7A and 7B.

In one embodiment, the configuration update module 510 updates aconfiguration parameter for a set of storage cells. The configurationupdate module 510, in certain embodiments, updates a configurationparameter in response to a change in one or more media characteristicscorresponding to the configuration parameter. The characteristic updatemodule 508 may notify the configuration update module 510 that thecharacteristic update module 508 has updated a media characteristic, theconfiguration update module 510 may periodically scan mediacharacteristics for changes, the configuration update module 510 maycheck media characteristics for changes in response to a configurationtrigger for a set of storage cells, or the like.

In certain embodiments, the configuration update module 510 updates aconfiguration parameter in response to a change in a mediacharacteristic that is greater than a predefined change threshold. Theconfiguration update module 510, in one embodiment, updatesconfiguration parameters in cooperation with the configuration parametermodule 504, using the configuration parameter module 504, or the like.The configuration update module 510, in another embodiment, may updateconfiguration parameters stored in a configuration parameter repository,as described in greater detail below with regard to FIGS. 8A and 8B.

In one embodiment, the adaptive configuration module 512 dynamicallyadjusts and adapts one or more configuration parameters, thresholds,management techniques, or the like for the non-volatile memory device102 and/or for the non-volatile memory media 110. In certainembodiments, the adaptive configuration module 512 may adjust or adaptas the non-volatile memory device 102 ages, as a use case for thenon-volatile memory device 102 changes, or the like. Examples of usecases may include a cache use case, an archival use case, a server usecase, an enterprise use case, a consumer use case, or the like.

The adaptive configuration module 512, in one embodiment, basesadjustments or adaptations on a priori knowledge for the non-volatilememory device 102, collected run-time statistics for the non-volatilememory device 102, media characteristics for storage cells of thenon-volatile memory device 102, or the like. Unlike magnetic storage,media attributes for non-volatile memory typically vary over a storagedevice's useful life. For example, storage regions of the non-volatilememory media 110 may be periodically processed for storage capacityrecovery or garbage collection to manage the impact of read disturbs andto ensure reliable data retention.

In non-volatile memory media 110, an effect called read disturb canoccur in unselected storage cells when adjacent storage cells areselected and read, causing charge to collect on the floating gates ofthe unselected storage cells making the unselected storage cells have anincreased voltage that has not been deliberately applied. One approachto combating the effects of read disturb, is to move valid data out ofthe disturbed cells while the values in those cells are stilldeterminable. The valid data may be re-written to a new physicallocation and the disturbed cells are erased to remove the effects of theread disturb. This approach is called a refresh and the time betweenrefresh operations is referred to as a data refresh interval. A readdisturb threshold is a number of reads of neighboring cells beforeremedial action is needed to mitigate the effects of read disturb. Adata refresh interval at which storage regions are processed for storagecapacity recovery and/or data refresh, that is appropriate for anon-volatile memory device 102 near an end of life may be too aggressivefor a non-volatile memory device 102 at the beginning of use.

The adaptive configuration module 512, in various embodiments, maydynamically adjust or adapt a data refresh interval based on an age (inabsolute time, in powered-on time, in an amount of user data written, orthe like) of the non-volatile memory device 102, a read disturbthreshold (e.g., a number of read operations before data is refreshed tomitigate effects of read disturb) based on wear of the non-volatilememory device 102, an erase block retirement policy based on an age ofthe non-volatile memory device 102, a garbage collection method for thenon-volatile memory device 102 based on host workload, garbagecollection by zone of the non-volatile memory device 102 based on levelsof extent activity to minimize stir between active and inactive data,scrubbing intervals to increase scrubbing as the non-volatile memorydevice 102 ages, or the like.

In one embodiment, the adjustment threshold module 514 cooperates withthe configuration parameter module 504 and/or the cell configurationmodule 506 to use a current configuration parameter setting for a set ofstorage cells in response to a target configuration parameter settingthat the configuration parameter module 504 determines for the set ofstorage cells being within a threshold range of the currentconfiguration parameter setting. For example, if a target configurationparameter, such as a read voltage threshold, is within a predefinedrange of a current setting for the configuration parameter, theadjustment threshold module 514 may determine not to adjust theconfiguration parameter to the target, but to use the current setting(e.g., a “no-op” or “gimme”). In certain embodiments, based ondifferences between target settings and current settings for a set ofconfiguration parameters, the cell configuration module 506 may set oneor more configuration parameters to their target settings, while leavingone or more other configuration parameters at their current settings.For example, the adjustment threshold module 514 may determine that thecell configuration module 506 sets one or two read voltage thresholdsfor a read operation, without setting the other read voltage thresholdsfor the particular read operation, because the target settings for theother read voltage thresholds may be within a threshold range of thecurrent settings, or the like.

The threshold range for the adjustment threshold module 514 may beselected such that errors caused by the difference between the targetsetting and the current setting are minimal, are correctable, or thelike. Configuring a set of storage cells to use a new configurationparameter setting, in certain embodiments, may incur overhead, increaselatency of a storage operation, or the like. Continuing to use a currentconfiguration parameter setting without reconfiguring the set of storagecells when a target setting is close to the current setting (e.g. withina threshold range) may remove the overhead or latency, thereby reducinga performance or latency impact of managing and adjusting configurationparameters.

The adjustment threshold module 514, in certain embodiments, may usedifferent threshold ranges for different sets of pages, differentabodes/storage states, or the like, customizing the threshold ranges. Inone embodiment, the configuration parameter module 504 may determine athreshold range for the adjustment threshold module 514 as aconfiguration parameter based on one or more media characteristics, orthe like. For example, a set of storage cells, abode, or the like thatis more prone to errors, leakage, interference, with a higher RBER, orthe like may have a smaller, narrower threshold range for adjustmentsthan a set of storage cells, abode, or the like that is less prone toerrors, leakage, interference, with a lower RBER, or the like. Incertain embodiments, the configuration parameter module 504 and/or thecell configuration module 506 may override a threshold range of theadjustment threshold module 514 based on a storage media characteristic,a background scan, or the like.

In one embodiment, the sparse adjustment module 516 cooperates with theconfiguration parameter module 504, the cell configuration module 506,and/or the adaptive configuration module 512 to use a defaultconfiguration parameter setting for a set of storage cells until thenon-volatile memory media 110 and/or the set of storage cells satisfy anage threshold. The default configuration parameter setting may includean initial setting, a previous setting, a current setting, amanufacturer recommended setting, or other default setting. The agethreshold may be a predetermined program/erase count, a predeterminederror rate, a predetermined temporal age, a predetermined powered-ontime, or the like for the non-volatile memory device 102, thenon-volatile memory media 110, and/or the set of storage cells.

The age threshold, in one embodiment, may be selected such that errorsthat occur prior to the age threshold being reached are minimal,correctable using ECC data, or the like. For example, in certainembodiments, the age threshold may be selected based on a number of biterrors that the ECC module 412 is configured to correct, so that thecell configuration module 506 does not adjust or reconfigure one or moreconfiguration parameters during a period when an ECC of the ECC module412 is sufficient to correct errors that are likely to occur. Theconfiguration parameter module 504, in a further embodiment, maydetermine different age thresholds for different storage regions, setsof pages, abodes, or the like. In certain embodiments, the likelihood oferrors, read disturb, voltage drift, and the like increases as thenon-volatile memory media 110 ages. By using a default configurationparameter until the age threshold is satisfied instead of reconfiguringstorage cells with new, adjusted configuration parameter settings, thesparse adjustment module 516 may remove or minimize the overhead andlatency associated with reconfiguring the storage cells, while errorsare typically infrequent and correctable.

In one embodiment, the backstop module 518, in cooperation with theadaptive configuration module 512 or the like, increases a frequency ofstorage capacity recovery operations, such as garbage collection orgrooming, for at least a subset of the non-volatile memory media 110over time. For example, the backstop module 518 may decrease the datarefresh interval over time to combat the effects of read disturb asdescribed above with regard to the adaptive configuration module 512. Inone embodiment, the configuration parameter module 504 may determine adata refresh interval for a set of storage cells as a configurationparameter based on media characteristics for the set of storage cells,such that different sets of storage cells have different storagecapacity recovery frequencies.

In this manner, in certain embodiments, the backstop module 518 mayprovide variable grooming, garbage collection, or other storage capacityrecovery thresholds or frequencies overtime as the non-volatile memorymedia 110 ages. In one embodiment, the backstop module 518 may manage asingle frequency of storage capacity recovery operations for the entirenon-volatile memory device 102. In a further embodiment, the backstopmodule 518 may manage frequencies of storage capacity recoveryoperations individually for logical or physical erase blocks of thenon-volatile memory media 110. The backstop module 518, in anotherembodiment, may manage frequencies of storage capacity recoveryoperations by group or set of logical or physical erase blocks of thenon-volatile memory media 110.

Increasing the frequency of storage capacity recovery operations, incertain embodiments, ensures that configuration parameter settings forstorage cells of the non-volatile memory media 110 are not adjustedbeyond a backstop value. For example, in some embodiments, thenon-volatile memory media 110 may become more susceptible to the effectsof read disturb over time, in some cases by a factor of ten or more.Instead of adjusting a configuration parameter such as a read voltagethreshold further and further over time to compensate for the increasingeffects of read disturb, by increasing the frequency of storage capacityrecovery options, the backstop module 518 places a backstop value or capon the configuration parameter adjustments used. Providing a backstopvalue or cap, in certain embodiments, may decrease bit errors, make datastorage more reliable, or the like.

FIG. 6A is a schematic block diagram illustrating one embodiment of anarray 600 of N number of storage elements 606. In the depictedembodiment, an ECC chunk 616 includes data 612 from several storageelements 606. In a further embodiment, ECC checkbits for the ECC chunk616 are also stored across several storage elements 606.

The array 600 of storage elements 606, in one embodiment, includes Nnumber of storage elements 606 a, 606 b, 606 c, . . . 606 n. Eachstorage element 606 may comprise a device, a chip, a portion of a chip,a die, a plane in a die, or the like. In the depicted embodiment, thestorage elements 606 a-n form a bank 602 a. The array 600, in oneembodiment, includes several banks 602 a . . . 602 m. The banks 602 a-m,in the depicted embodiment, include several channels 604 a, 604 b, 604c, . . . , 604 n. In one embodiment, a packet or data set is writtenacross the several channels 604 a-n and data is read separately fromeach channel 604 a-n and reassembled into the packet. In anotherembodiment, an ECC chunk 616, packet, or data set is written across theseveral channels 604 a-n and data is read in parallel from all thechannels 604 a-n. One read operation on a bank 602 a may read a wholeECC chunk 616, packet, or data set or a portion of an ECC chunk 616,packet, or data set that is reassembled into a whole ECC chunk 616,packet, or data set. In the depicted embodiment, each channel includesat least one storage element 606 in each bank 602.

Furthermore, in one embodiment each storage element 606 includes aphysical erase block or “PEB” 608. For example, storage element one 606a includes PEB one 608 a. A physical erase block is typically an eraseblock located on one die, chip, or other storage element 606. Each PEB608 includes m physical pages 610. For example, PEB one 608 a includespage 0 610 a . . . page m 614 a, PEB 2 608 b includes page 610 b . . .page m 614 b, PEB 3 608 c includes page 0 610 c . . . page m 614 c, andPEB m 608 m includes page 0 610 m . . . page m 614 m. Each physical page610 a stores a portion of data (“D 0, D 1, . . . , D m”) 612 and ECCcheckbits distributed with the data 612.

In one embodiment, a group of PEBs (PEB 1 608 a-PEB m 608 m) forms alogical erase block (“LEB”). An LEB may span the array of N storageelements 600. In certain embodiments, an LEB is sized to fit within abank 602 a-m, with one PEB 608 a-m from each storage element 606 a-n orthe like. In other embodiments, a LEB may span different banks 602 a-mand may include one or more PEBs 608 a-m from multiple banks 602 a-m.Furthermore, in an embodiment, a logical page (“LP”) spans a pluralityof physical pages 610 in a row. In another embodiment a logical pagespans N storage elements 606 a-n.

In one embodiment, the ECC is a block code that is distributed with thedata. Furthermore, the data and the ECC may not align with anyparticular physical hardware boundary. As a result, error correctionwith the ECC codes is not dependent on a particular hardwareconfiguration. Therefore, the ECC and corresponding data may form an ECCchunk 616 and the ECC chunk 616 may be divided and stored on one or moreof the N storage elements 606 a-n. An ECC chunk 616 typically spans atleast a portion of a plurality of physical pages 610 of a logical pagewhere the data and ECC generated from the data 612 a, 612 b, . . . 612 mare spread across the N storage elements 606 a-n. In one embodiment, aLP includes a plurality of ECC chunks 616. A physical page 610 maycontain one or more data bytes of the ECC chunk 616. An ECC chunk 616may span multiple rows within a physical page 610 and a physical page610 may include a plurality of ECC chunks 616.

Because, in the depicted embodiment, the ECC checkbits for the ECC chunk616 are distributed across several storage elements 606 a-n and channels604 a-n, when a data error occurs due to a read voltage shift in one ormore of the storage elements 606 a-n, the ECC module 412 may not be ableto determine which storage elements 606 have an error that iscorrectable by adjusting the read voltage threshold. In one embodiment,the distribution module 414 determines which storage elements 606 orchannels 604 have data with a read bias that is outside an expecteddistribution of the known bias, and the configuration module 352 adjuststhe read voltage thresholds of the storage elements 606 determined bythe distribution module 414.

In one embodiment, the deviation module 404, the ECC module 412, and/orthe distribution module 414 determines that a data set has an error or aread bias that deviates from the known bias, and the data set sourcemodule 422 determines from which storage element 606 the data set wasread. For example, in one embodiment, the array 600 may have 24 channels604, and 8 bytes may be read in parallel from 24 storage elements 606 ofa single bank 602 during a read operation for a total of 192 bytes perread operation. Based on this information, the data set source module422, in one embodiment, can determine from which storage element 606 adata set was read based on the position of an 8 byte data set within the192 bytes. In one embodiment, the 192 bytes comprise the ECC chunk 616.

By comparing read biases of data from each of the channels 604 a-n tothe known bias, the configuration module 352 can correct data errorsthat occur due to changes in read voltages for particular channel(s)even without the use of ECC checkbits. Without comparing the read biasesof data from the channels 604 a-n to the known bias, adjustment of theread voltage thresholds would require a large number of trial-and-errortests adjusting and testing every possible read voltage thresholdadjustment for each possible combination of channels 604 a-n. Bycomparing the read biases of data from the channels 604 a-n to the knownbias, the configuration module 352 can determine exactly which channel604 to adjust. By determining the direction of deviation for thosechannels, the configuration module 352 further decreases the searchspace for the read voltage thresholds for those channels by half. Toillustrate the potential size of the search space for a suitableadjusted read voltage threshold, suppose an ECC chunk 616 (e.g., ECCcode word—comprising both data and the corresponding ECC checkbits) isstored on the storage elements 606 a-606 n. Further suppose that thestorage elements 606 a-606 n in a row of the array 600 that stores theECC chunk 616 each have an independent adjustable read voltagethreshold. For example, in one embodiment, the number of differentcombinations of read voltage threshold settings for the array 600 with ηchannels 604 a-n, λ number of levels at which the read voltage thresholdcan be set per channel, and x number of channels that have a readvoltage threshold that needs to be adjusted is given by equation 1:

$\begin{matrix}{{f\left( {x,\eta,\lambda} \right)} = {\begin{pmatrix}\eta \\x\end{pmatrix} \cdot \lambda^{x}}} & (1)\end{matrix}$

The number of different combinations of read voltage threshold settingsfor the array 600 with all permutations of up to η channels 604 a-n, inone embodiment is given by equation 2:

g(x,η,λ)=Σ_(i=1) ^(x) f(i,η,λ)  (2)

Using equation 1, for example, if there are twenty-four channels 606 a-n(η=24), eight possible read voltage threshold settings for each channel606 (λ=8), and only two of the twenty-four channels 606 a-n have readvoltage thresholds that need to be adjusted (x=2), there are 17,644total different combinations of read voltage threshold settings. If thenumber of channels 606 with read voltage thresholds that need adjustingincreases to three, the number of different combinations increases to1,036,288. The configuration module 352 drastically reduces thesenumbers by detecting which channels 606 a-n have read voltage thresholdsthat need adjusting. In addition, comparing the known bias of the dataon the media in a storage grouping to the current bias indicates thedirection to adjust the read voltage thresholds. Knowing the directionin which to adjust the read voltage threshold greatly reduces the searchspace for a suitable voltage in the channels known to have a data error.

Consequently, the number of combinations that may need to be attemptedchanges from 17,644 where x=2 to 32 and from 1,036,288 where x=3 to 256,because the configuration module 352 uses the known bias to determinewhich channels have read voltage thresholds that need adjusting and thedirection of the adjustment. However, each of these combinations may notneed to be tried because as the adjustments are iteratively made, theknown bias of the data continues to indicate which direction to makeeach subsequent adjustment, potentially cutting the search space atleast in half with each iteration. Various search algorithms can be usedto quickly identify a suitable adjusted read voltage threshold. (e.g., abinary search).

FIG. 6B is a schematic block diagram illustrating one embodiment of anarray 650 of N storage elements 606. The array 650, in the depictedembodiment, is substantially similar to the array 600 of FIG. 6A, butwith the ECC chunk 652 including data 612 a in a single storage element606 a, instead of across several storage elements 606 a-n. In oneembodiment, ECC checkbits for the ECC chunk 652 are stored in the singlestorage element 606 a. Because each storage element 606 a-n or channel604 a-n has separate ECC checkbits, in one embodiment, the ECC module412 uses the separate ECC checkbits to determine in which storageelements 606 a-n or channels 604 a-n an error has occurred, and theconfiguration module 352 adjusts the read voltage thresholds of theparticular storage element(s) 606 determined by the ECC module 412.

FIG. 6C shows one embodiment of configuration parameters 662 a-c for aset of multi-level storage cells, such as MLC NAND flash storage cells,or the like, with an example encoding or programming model. Anylimitations inherent in the represented encoding model do notnecessarily apply to all other encoding models, and the presentdisclosure should not be construed as inherently containing any suchlimitations. The read voltage states, in the depicted embodiment, areencoded using a Gray code encoding model, with binary values foradjacent states differing by a single bit in the encoding.

FIG. 6C shows that the value “11” is associated with the lowest readvoltage state (labeled L0, an “erase” state), the value “01” isassociated with the next lowest read voltage state (labeled L1), thevalue “00” is associated with the next highest read voltage state(labeled L2), and the value “10” is associated with the highest readvoltage state (labeled L3). In FIG. 6C, the lowest read voltage state L0is depicted as a negative voltage below the depicted 0.0V. Values,magnitudes, sizes, and the like of read voltages may vary bymanufacturer and type of non-volatile memory cell, each of which areencompassed by the present disclosure. The configuration parameters 662,in the depicted embodiment, are read voltage thresholds 662 thatseparate states L0, L1, L2, and L3, as described above.

The non-volatile memory controller 104 interprets the four discretelevels of voltage stored in the multi-level storage cell as representingtwo binary bits one represented by a most significant bit (MSB) in thecell encoding and one represented by a least significant bit (LSB) inthe cell encoding. As explained above, other programming and encodingmodels may be used. Also, certain non-volatile memory media 110 may havemore than four possible states, allowing more than two binary values tobe stored in a single multi-level storage cell. The voltage levels L0,L1, L2, and L3 may or may not be contiguous; for example, in certainembodiments, the voltage levels are separated by band gaps known asguard band. For example, L0 and L1 may be separated by 0.3V.

In one embodiment, the LSB corresponds to a lower page of data and theMSB corresponds to an upper page of data. In certain embodiments, themulti-level storage cell may adhere to a two-phase programming model,described below, which requires that the LSB be written to before theMSB can be written or vice versa. In another embodiment, the LSB and MSBmay be programmed separately by the non-volatile memory controller 104.Such an approach may be taken due to vendor or manufacturer requirementsfor page pairing (e.g., a LSB bit of MLC cell is paired with an MSB bitof a different MLC cell) and page addressing (e.g., LSB page must beprogrammed before the MSB page or vice versa). In certain instances, theLSB must be written before the MSB is written, the MSB must be writtenbefore the LSB is written, or the like.

In certain embodiments, the non-volatile memory media 110 may employ atwo-phase programming model. In such a model, a binary value is firstwritten to the LSB by way of a first write command to the lower page.The write command causes the multi-level storage cell to move from itsinitial state (for example, a 11 state in L0) to an intermediate state(the lower-to-middle LM state—between L1 and L2) configured such that a00 state is subsequently read. For example, writing a “0” to the lowerpage causes the multi-level storage cell to change from the L0 state(where both the LSB and the MSB are 1) to the L2 state (where the LSB ischanged to a 0). A subsequent write of a “0” to the upper page moves themulti-level storage cell from the intermediate state (typically betweenthe L1 state and the L2 state) to L2 state such that both bits of theMLC are “0”. Thus, in such an embodiment, two writes (one to the lowerpage and one to the upper page) are needed to move the multi-level cellfrom L0 to L2, since the cell transitions through the intermediate stateand the MLC device requires that the lower page be programmed before theupper page and does not allow partial programming of a page without anintervening erase operation. Writing a “1” to either of the upper pageor lower page will cause the MLC to transition to either L1 or L3depending on the binary value of the lower page at the time. Inaddition, certain non-volatile memory media vendors may impose arequirement that the lower page must be written to before the upperpage, or the like. In other embodiments, the non-volatile memory media110 may employ a two-phase programming model where a binary value isfirst written to the MSB by way of a first write command to the upperpage.

In certain embodiments, the configuration parameter module 504determines and manages read voltage thresholds 662 or otherconfiguration parameters individually for one or more of the abodes L0,L1, L2, L3, determining different settings or adjustments toconfiguration parameters in different abodes L0, L1, L2, L3. In oneembodiment, the configuration module 352 adjusts one or more readvoltage thresholds 662 based on a subset of binary data that multi-levelstorage cells store, such as just an upper page, just a lower page, orthe like. In such embodiments, examining the state changes for the LSBbit(s) indicate the direction the voltage in the multi-level storagecell is changing. For both Gray code encoding (as depicted in FIG. 6C)and binary code encoding of bit values, the LSB of a multi-level storagecell transitions between a binary zero and a binary one between themiddle two abodes or states, the L1 state and the L2 state in thedepicted embodiment.

For other encoding models, the MSB may transition between a binary zeroand a binary one between the middle two abodes or states, or the like.For Gray code or binary code encoding models, the LSB has a value of “1”for read voltages in a lower range (including the lower two states orabodes, L0 and L1) and the LSB has a value of “0” for read voltages inan upper range (including the upper two states or abodes, L2 and L3). Byusing just the LSB of MLC storage cells to determine whether a read biasdeviates from a known bias, the configuration module 352, in oneembodiment, may make the determination in a substantially similar mannerto determining whether a read bias for SLC storage cells deviates from aknown bias, by counting or tallying binary ones and/or binary zeroes ofan LSB data set, or the like.

For certain types of multi-level storage cells, the middle read voltagethreshold 662 b and the adjacent L1 and L2 states may be more sensitiveto read disturb or other factors that can cause read voltages to drift.Further, as described above, in certain embodiments, the LSB and the MSBof a single multi-level storage cell may represent data stored indifferent physical pages. Using a single bit from each of a plurality ofmulti-level storage cell as a data set, in one embodiment, may reduce anumber of read operations to retrieve the data set. In otherembodiments, use of a single bit from each of a plurality of multi-levelstorage cells in the lower page simplifies a process of detecting adeviation and direction of a read bias from a known bias for multi-levelstorage cells.

In one embodiment, the direction module 406 determines a direction ofdeviation for a grouping of multi-level storage cells based on a dataset that includes data from one or more lower pages of the multi-levelstorage cells. Because the lower pages include the LSBs, in certainembodiments, the direction module 406 determines that a read voltagethreshold 662 deviates toward a larger read voltage in response to adifference between a read bias for the lower pages and a known bias forthe lower pages indicating that storage cell values for the LSBs havetransitioned from a binary one to a binary zero. For an LSB totransition from a binary one to a binary zero, a read voltage for amulti-level storage cell using the encoding model of FIG. 6C must driftfrom either an L0 or L1 state to an L2 or L3 state, indicating that oneor more of the read voltage thresholds 662 should be increased, to placethe read voltage back in the original L0 or L1 state.

Similarly, in certain embodiments, the direction module 406 determinesthat a read voltage threshold 662 deviates toward a smaller read voltagein response to a difference between a read bias for the lower pages anda known bias for the lower pages indicating that storage cell values forthe LSBs have transitioned from a binary zero to a binary one. For anLSB to transition from a binary zero to a binary one, a read voltage fora multi-level storage cell using the encoding model of FIG. 6C mustdrift from either an L3 or L2 state to an L1 or L0 state, indicatingthat one or more of the read voltage thresholds 662 should be decreased,to place the read voltage back in the original L3 or L2 state. Incertain embodiments, a deviation across multiple states may be unlikely,and deviations detectable using LSBs may be between the L1 and L2states, indicating a clear direction of deviation in either direction.

In another embodiment, the direction module 406 determines a directionof deviation based at least partially on an encoding type used forstorage cells of the non-volatile memory media 110, a physical and/orelectrical architecture of the storage cells of the non-volatile memorymedia 110, or the like. For example, based on the encoding model of FIG.6C, the direction module 406 may determine a direction of deviationbased on a 2-bit MLC media type, based on whether the data set includesan upper page or a lower page, based on the depicted Gray code encodingtype, based on a magnitude of the determined deviation, or the like. Ina further embodiment, the direction module 406 may transform or combineLSBs and MSBs from separate or disparate addresses, such as differentphysical pages or the like, into a single data set or may otherwisecoordinate LSBs and MSBs to determine a direction of deviation.

Using each bit stored in multi-level storage cells to determine a readvoltage threshold adjustment, in certain embodiments, can increase theaccuracy of the read voltage threshold adjustment, but may increase thenumber of read operations or add complexity to the determination. In oneembodiment, if the ECC decoder 322 detects a data error in an upper pageof a grouping of multi-level storage cells, the data set read module 402retrieves one or more lower pages for the grouping and the configurationmodule 352 adjusts a read voltage threshold for the grouping based onthe lower pages.

FIG. 6D depicts one embodiment of adjusted configuration parameters 664a-c for a set of multi-level storage cells of non-volatile memory media110. In certain embodiments, the configuration parameters 662 a-c ofFIG. 6C are default configuration parameters, set by a manufacturer, avendor, or the like and the configuration module 352 and/or theproactive configuration module 424 adjust or configure the defaultconfiguration parameters 662 a-c to the adjusted configurationparameters 664 a-c. The configuration parameter module 504, in oneembodiment, determines different adjustments 666 a-c to the defaultconfiguration parameters 662 a-c resulting in the different adjustedconfiguration parameters 664 a-c. In the depicted embodiment, theconfiguration parameter module 504 determines the different adjustments666 a-c individually for the different abodes L0, L1, L2, L3, withdifferent magnitudes, different directions, and the like, customizingthe different adjusted configuration parameters 664 a-c individually tomedia characteristics of the different abodes L0, L1, L2, L3.

The adjusted configuration parameters 664 a-c more closely match theactual distributions of storage cell states of FIG. 6D than do thedefault configuration parameters 662 a-c. Were a corresponding set ofstorage cells to use the default configuration parameters 662 a-c withthe distributions of storage cell states of FIG. 6D, the portions of thedistributions that have drifted past the locations of the defaultconfiguration parameters 662 a-c would register data errors. Similarly,because the charge levels of the different abodes L0, L1, L2, L3 havedrifted, leaked, been disturbed, or the like by different amounts and indifferent directions, using the same adjustment 664 for each abode L0,L1, L2, L3, in certain embodiments, may register data errors. Byconfiguring the corresponding set of storage cells to use theindividually adjusted configuration parameters 664 a-c, theconfiguration module 352 and the configuration parameter module 504prevent, avoid, or correct the potential data errors.

In one embodiment, the configuration module 352 determines the adjustedconfiguration parameters 664 a-c reactively using the deviation module404, the direction module 406, the adjustment module 408, or the like,as described above. In another embodiment, the configuration module 352determines the adjusted configuration parameters 664 a-c proactivelyusing the proactive configuration module 424, the media characteristicmodule 502, and the configuration parameter module 504, based on mediacharacteristics for a corresponding set of storage cells, as describedabove.

FIG. 6E depicts one embodiment of raw bit error rates (“RBERs”) 674 forpages 676 after a retention time has passed. In the graphs of FIGS. 6Ethrough 6F, the peaks or extremities of the waveforms represent the RBER674 for a page 676, as the RBERs 674 alternate or oscillate between evenand odd pages 676, upper (e.g. MSB) and lower (e.g. LSB) pages 676, orthe like, in the depicted embodiments. Certain non-volatile memory media110, such as all-bit-line media, may have RBERs 674 that vary betweenupper and lower pages 676 but not between even and odd pages 676. Othernon-volatile memory media 110 may have RBERs 674 that vary for bothupper and lower pages 676 and for even and odd pages 676, just for evenand odd pages 676, or the like. In further embodiments, RBERs 674 forpages 676 may be substantially smooth, with little or no oscillationbetween pages 676.

The pages 676 of FIG. 6E are grouped into a first set 678 of pages 676and a second set 680 of pages 676 based on the RBERs 674 of the pages676. In the embodiment depicted in FIG. 6E, the first set 678 of pages676 have higher RBERs 674 than the second set 680 of pages 676. Thefirst set 678 of pages 676, for example, may include even pages withhigher RBERs 674 than odd pages in the second set 680 of pages 676, orvice versa. Even pages may have higher RBERs 674 than odd pages, or viceversa, due to the effects of program disturb or the like. In anotherembodiment, the first set 678 of pages 676, for example, may includeupper pages of multi-level storage cells with higher RBERs 674 thanlower pages of the multi-level storage cells in the second set 680 ofpages 676, or the like. The media characteristic module 502 mayreference, determine, or maintain different media characteristics forthe different sets 678, 680 of pages 676 and the configuration parametermodule 504 may determine different configuration parameter settings forthe different sets 678, 670 of pages 676 based on the different mediacharacteristics, such as the different RBERs 674 or the like.

FIG. 6F depicts another embodiment of RBERs 674 for pages 676 after aretention time has passed. In FIG. 6F, the pages 676 are grouped into afirst set 682 of pages 676, a second set 684 of pages 676, and a thirdset 686 of pages 676 based on the RBERs 674 of the pages 676. The RBERs674 for the pages 676 in the embodiment of FIG. 6F are substantiallysimilar to the embodiment of FIG. 6E, except one or more pages 676toward each end of the pages 676 have higher RBERs 674.

In FIG. 6F, the one or more pages 676 toward each end of the pages 676with the highest RBERs 674 are part of the first set 682. In certainembodiments, the pages 676 of the first set 682 may comprise one or morepages toward a first end of the upper pages of multi-level storage cellsand one or more pages toward a second end of the upper pages, such asthe first two upper pages and the second-to-last upper page, or thelike. The second set 684 of pages 676 may include the rest of the upperpages, while the third set 686 of pages 676 may include the lower pagesof the multi-level storage cells, or the like. The media characteristicmodule 502 may reference, determine, or maintain different mediacharacteristics for the different sets 682, 684, 686 of pages 676 andthe configuration parameter module 504 may determine differentconfiguration parameter settings for the different sets 682, 684, 686 ofpages 676 based on the different media characteristics, such as thedifferent RBERs 674 or the like.

FIG. 6G depicts another embodiment of RBERs 674 for pages 676 after aretention time has passed. The pages 676 of FIG. 6G are grouped into afirst set 688 of pages 676, a second set 690 of pages 676, and a thirdset 688 of pages 676 based on the RBERs 674 of the pages 676. The RBERs674, in the embodiment depicted in FIG. 6G, have a teeter-totterconfiguration and the pages 676 are chopped or divided into the sets688, 690, 692 of pages 676 based on contiguous ranges of RBERs 674. Thedepicted sets 688, 690, 692 of pages 676, in further embodiments, may besubdivided into additional sets of pages 676, and the configurationparameter module 504 may determine different configuration parametersfor the additional subdivided sets. For example, the pages 676 towardthe middle of the set 690, at the center of the depicted teeter-totterconfiguration, may comprise a separate set of pages 676 for which theconfiguration parameter module 504 determines a different configurationparameter or the like. In certain embodiments, the configurationparameter module 504 may use an average RBER 674 for the pages 676 of aset 688, 690, 692 to determine a configuration parameter for the pages676 of the set 688, 690, 692.

The example embodiments depicted in FIGS. 6E, 6F, and 6G are forpurposes of illustration and are non-limiting. The RBERs 674 for pages676 may vary based on vendor, architecture and geometry of thenon-volatile memory media 110, usage patterns, or the like, and otherembodiments may have different amounts of sets of pages, differentconfigurations for sets of pages, or the like.

FIG. 7A depicts one embodiment of the media characteristic module 502and a media characteristic repository 702. In the depicted embodiment,the media characteristic module 502 stores and maintains mediacharacteristics for a plurality of different sets of storage cells in amedia characteristic repository 702. The media characteristic repository702 stores entries reciting media characteristics for sets of storagecells of the non-volatile memory media 110. The media characteristicrepository 702 may be embodied by one or more of a table, a matrix, anarray, a database, a file, or another data structure that stores mediacharacteristics.

The media characteristic module 502 may store the media characteristicrepository 702 in one or more of a metadata area of the non-volatilememory media 110, in volatile memory of the non-volatile memory device102 and/or of the computer 112, in a configuration file for thenon-volatile memory device 102 stored in other non-volatile storage ofthe computer 112, in dedicated non-volatile storage of the non-volatilememory device 102, or the like. The media characteristic module 502 maystore the media characteristic repository 702 and/or mediacharacteristics in a single location, or may divide storage betweenmultiple locations.

For example, in one embodiment, the media characteristic module 502 mayaccess static media characteristics such as a make, a model, amanufacturer, a product version, or the like for the non-volatile memorydevice 102 and/or the non-volatile memory media 110 from nonvolatilestorage of the non-volatile memory device 102, such as in a programmableread only memory (“PROM”) or the like that is programmed by amanufacturer or vendor. The media characteristic module 502 may storedynamic media characteristics, such as a program/erase cycle counts,read counts, retention times, temperatures, use cases, error statistics,and the like in volatile memory of the non-volatile memory device 102and/or of the computer 112, metadata on the non-volatile memory media110, or the like. If the media characteristic module 502 stores at leasta portion of the media characteristic repository 702 in volatile memory,in certain embodiments, the media characteristic module 502 mayperiodically save data of the media characteristic repository 702 to thenon-volatile memory media 110 or to other nonvolatile storage so thatthe media characteristic module 502 may rebuild a media characteristicrepository 702 in response to a power failure, an improper shutdown, orthe like.

FIG. 7B depicts another embodiment of the media characteristicrepository 702. The media characteristic repository 702 includes aplurality of entries 708 for sets of storage cells. The sets of storagecells, in the depicted embodiment, are organized by storage region 706,with an entry 708 in the media characteristic repository 702 for eachstorage region 706 from LEB 0 through LEB N. While the storage regions706 in the depicted embodiment are illustrated as logical erase blocksLEB 0 through LEB N, as described above, in other embodiments, a storageregion 706 may include a physical erase block, a page (logical orphysical), a set of pages, an ECC chunk/codeword, a division within apage, a storage state of a storage cell, an abode of a storage cell, adie, a plane in a die, a chip, or the like.

Each entry 708 further includes media characteristics 704 for thecorresponding storage region 706. The media characteristics 704, in thedepicted embodiment, include a program/erase (“P/E”) cycle count 704 a,a read count 704 b, a retention time 704 c, a temperature 704 d, and abit error rate 704 e. The characteristic update module 508 may cooperatewith the media characteristic module 502 to update the mediacharacteristic repository 702 as described above.

In the depicted embodiment, the P/E cycle count 704 a varies between 0.7k and 2.0 k, (i.e., between 700 and 2000, “k” representing 1000).Similarly, the read count 704 b varies between 0.5 k and 4.1 k (i.e.,between 500 and 4100). The retention time 704 c varies from 10 min(minutes) to 100 min, and the temperature 704 d varies from 43° C.(degrees Celsius) to 48° C. Lastly, the bit error rate 704(e) variesbetween 9.7E-5 (9.7 times 10 to the −5th power or 0.000097) and 2.5E-4(2.5 times 10 to the −4th power or 0.00025). The depicted storage mediacharacteristics 704 are representative examples, and are not limiting;in light of this disclosure it is clear that storage mediacharacteristics 704 outside the depicted ranges are possible, as well asother types of storage media characteristics 704 not depicted in FIG.7B.

FIG. 8A depicts one embodiment of the configuration parameter module 504and a configuration parameter repository 802. In the depictedembodiment, the configuration parameter module 504 stores and maintainsconfiguration parameters for a plurality of different sets of storagecells in a configuration parameter repository 802. In certainembodiments, the configuration parameter repository 802 may beintegrated with the media characteristic repository 702 in a singlerepository 702, 802. The configuration parameter repository 802 storesentries reciting configuration parameters for sets of storage cells ofthe non-volatile memory media 110. The configuration parameterrepository 802 may be embodied by one or more of a table, a matrix, anarray, a database, a file, or another data structure that storesconfiguration parameters.

FIG. 8B depicts another embodiment of a configuration parameterrepository 802. The configuration parameter repository 802 includes aplurality of entries 808 for sets of storage cells. The sets of storagecells, in the depicted embodiment, are organized by storage region 706,and the entries 808 correspond to storage regions 706 from LEB 0 throughLEB N. Each entry 808 further includes configuration parameters 804 forthe corresponding storage region 706. The configuration parameters 804,in the depicted embodiment, include read voltage threshold adjustments804 a-c for read level R1 804 a, read level R2 804 b, and read level R3804 c, with each entry as a hexadecimal offset from default read voltagethresholds. For example, in the depicted embodiment, the read voltagethreshold adjustments 804 a-c vary between FAh (a hexadecimal numbercorresponding to decimal number −6, in a two's complement representationwhere “h” represents hexadecimal) and 05h (a hexadecimal numbercorresponding to decimal number 5), including values such as 01h, 02h,04h, FEh, FCh, FDh, FAh, 03h, and 05h.

While the configuration parameters 804 in the depicted embodiment areillustrated as read voltage threshold adjustments, as described above,in other embodiments, configuration parameters 804 may includeresistivity thresholds, write or program thresholds, erase thresholds,and/or other modifiable parameters of the non-volatile memory media 110.Further, the three configuration parameters 804 a-c are provided by wayof example and, in other embodiments, other amounts and types ofconfiguration parameters may be included. For example, in oneembodiment, certain 20 nm non-volatile memory media 110, or the like,may have ten different read voltage thresholds R1-R10, set usingdifferent registers or the like, and the configuration parameter module504 may determine different values for R1-R10 for different sets,groups, storage regions, and/or different abodes/storage states. Asdescribed above, a configuration parameter 804 may include an absolutedata value, an offset or adjustment to a data value, or anotherparameter. The configuration update module 510 may cooperate with theconfiguration parameter module 504 to update the configuration parameterrepository 802 as described above.

Flow Chart

FIG. 9 depicts one embodiment of a method 900 for managing non-volatilememory media 110. The method 900 begins and the media characteristicmodule 502 references or otherwise determines 902 one or more mediacharacteristics for non-volatile memory media 110, such as an eraseblock (logical or physical), a page (logical or physical), a set ofpages, an ECC chunk/codeword, a division within a page, a storage stateof a storage cell, an abode of a storage cell, a die, a plane in a die,a chip, or the like. The configuration parameter module 504 determines904 different configuration parameter settings for different sets ofpages, different abodes/storage states, or the like of the non-volatilememory media 110 to use the different configuration parameter settingsand the method 900 ends.

FIG. 10 depicts another embodiment of a method 1000 for managingnon-volatile memory media 110. The method 1000 begins and thecharacteristic update module 508 determines 1002 whether or not anupdate event has occurred for a set of storage cells of the non-volatilememory media 110, such as an erase block (logical or physical), a page(logical or physical), a set of pages, an ECC chunk/codeword, a divisionwithin a page, a storage state of a storage cell, an abode of a storagecell, a die, a plane in a die, a chip, or the like. If thecharacteristic update module 508 determines 1002 that an update eventhas occurred, the characteristic update module 508 updates 1004 one ormore media characteristics for the non-volatile memory media 110, in amedia characteristic repository 702 or the like. If the characteristicupdate module 508 determines 1002 that an update event has not occurred,the characteristic update module 508 does not update 1004 the one ormore media characteristics.

The configuration update module 510 determines 1006 whether or not thereis a change in one or more media characteristics, due to thecharacteristic update module 508 updating 1004 the one or more mediacharacteristics or the like. If the configuration update module 510determines 1006 that there is a change in the one or more mediacharacteristics, the media characteristic module 502 determines 1008 oneor more media characteristics for the non-volatile memory media 110 andthe configuration parameter module 504 and/or the configuration updatemodule 510 determines 1010 different configuration parameters fordifferent divisions of the non-volatile memory media 110, such asdifferent erase blocks (logical or physical), pages (logical orphysical), sets of pages, ECC chunks/codewords, abodes/storage states ofstorage cells, die, planes in a die, chips, or the like. If theconfiguration update module 510 determines 1006 that there is no changein the one or more media characteristics for the non-volatile memorymedia 110, the method 1000 skips the referencing 1008 step and thedetermining/updating step 1010.

The cell configuration module 506 determines 1012 whether or not aconfiguration trigger has occurred. If the cell configuration module 506determines 1012 that a configuration trigger has occurred, the cellconfiguration module 506 configures 1014 the non-volatile memory media110 to use the determined 1010 different configuration parametersettings and the method 1000 repeats. If the cell configuration module506 determines 1012 that no configuration trigger has occurred, themethod 1000 repeats.

A means for determining media characteristics for non-volatile memorymedia 110, in various embodiments, may include a non-volatile memorycontroller 104, a non-volatile memory device controller 202, a devicefactor module 354, an inverse bias module 332, an ECC decoder 322, aconfiguration module 352, a proactive configuration module 424, a mediacharacteristic module 502, a characteristic update module 508, a mediacharacteristic repository 702, other logic hardware, and/or otherexecutable code stored on a computer readable storage medium. Otherembodiments may include similar or equivalent means for determiningmedia characteristics for non-volatile memory media 110.

A means for determining different configuration parameter settings fordifferent sets of pages of non-volatile memory media 110 based on mediacharacteristics, in various embodiments, may include a non-volatilememory controller 104, a non-volatile memory device controller 202, aconfiguration module 352, a direction module 406, an adjustment module408, a proactive configuration module 424, a configuration parametermodule 504, a configuration update module 510, an adjustment thresholdmodule 514, a sparse adjustment module 516, a backstop module 518, aconfiguration parameter repository 802, other logic hardware, and/orother executable code stored on a computer readable storage medium.Other embodiments may include similar or equivalent means fordetermining different configuration parameter settings for differentsets of pages of non-volatile memory media 110 based on mediacharacteristics.

A means for configuring non-volatile memory media 110 to use thedifferent configuration parameter settings for different sets of pages,in various embodiments, may include a non-volatile memory controller104, a non-volatile memory device controller 202, a configuration module352, an adjustment module 408, a write voltage module 416, a proactiveconfiguration module 424, a cell configuration module 506, other logichardware, and/or other executable code stored on a computer readablestorage medium. Other embodiments may include similar or equivalentmeans for configuring non-volatile memory media 110 to use the differentconfiguration parameter settings for different sets of pages.

A means for using a default setting for a set of pages in response toone or more of a target setting being within a threshold range of thedefault setting and the set of pages failing to satisfy an agethreshold, in various embodiments, may include a non-volatile memorycontroller 104, a non-volatile memory device controller 202, aconfiguration module 352, a proactive configuration module 424, aconfiguration parameter module 504, a configuration update module 510,an adjustment threshold module 514, a sparse adjustment module 516, abackstop module 518, a configuration parameter repository 802, otherlogic hardware, and/or other executable code stored on a computerreadable storage medium. Other embodiments may include similar orequivalent means for using a default setting for a set of pages inresponse to one or more of a target setting being within a thresholdrange of the default setting and the set of pages failing to satisfy anage threshold.

The present disclosure may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the disclosure is, therefore,indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed is:
 1. A method comprising: determining a configurationparameter for a set of storage cells of a solid state recording medium;reading data from the set of storage cells using the determinedconfiguration parameter; and adjusting the configuration parameter basedon the read data.
 2. The method of claim 1, further comprising:re-reading the data from the set of storage cells using the adjustedconfiguration parameter; and readjusting the configuration parameterbased on the re-read data.
 3. The method of claim 1, wherein adjustingthe configuration parameter based on the read data is performedreactively in response to a trigger and the read data comprises closedloop feedback data from the set of storage cells.
 4. The method of claim1, wherein determining the configuration parameter is based on one ormore media characteristics for the set of storage cells such that theconfiguration parameter is determined proactively in an open loop mannerwithout feedback from the set of storage cells.
 5. The method of claim1, wherein the configuration parameter comprises a read voltagethreshold for the set of storage cells.
 6. The method of claim 1,further comprising: storing different configuration parameters fordifferent sub-groupings of the set of storage cells; and reconfiguringthe entire set of storage cells to use one of the differentconfiguration parameters in response to a storage request for asub-grouping associated with the one of the different configurationparameters.
 7. The method of claim 1, wherein adjusting theconfiguration parameter comprises adjusting a guard band, the guard bandcomprising a separation distance between voltage abodes for the set ofstorage cells.
 8. The method of claim 1, wherein adjusting theconfiguration parameter comprises adjusting multiple read voltagethresholds for each storage cell of the set of storage cells.
 9. Themethod of claim 8, wherein the multiple read voltage thresholds areadjusted using a single command.
 10. The method of claim 1, whereinadjusting the configuration parameter comprises reducing a programvoltage for the set of storage cells over time.
 11. The method of claim1, further comprising decreasing a data refresh interval for the set ofstorage cells over time, the data refresh interval comprising aninterval at which a storage capacity recovery operation is performed forthe set of storage cells.
 12. An apparatus comprising: a configurationparameter module configured to determine a read voltage threshold forone or more NAND flash storage cells; a storage cell configurationmodule configured to configure the one or more storage cells to use thedetermined read voltage threshold; and an adjustment module configuredto adjust the read voltage threshold based on closed loop feedback fromthe one or more NAND flash storage cells.
 13. The apparatus of claim 12,wherein the adjustment module is configured to make a same adjustment tothe read voltage threshold for one or more of an erase block, a page, aset of pages, an error-correcting code (ECC) codeword, a division withina page, a die, a plane of a die, and a chip comprising the one or moreNAND flash storage cells.
 14. The apparatus of claim 12, furthercomprising a data set read module configured to read data from the oneor more NAND flash storage cells in response to a trigger, the read datacomprising the closed loop feedback.
 15. The apparatus of claim 14,wherein the trigger comprises one or more of a read request for the setof storage cells, an uncorrectable error for the data of the set ofstorage cells, a startup operation for a device comprising the set ofstorage cells, a time interval, and a regular shutdown operation for adevice comprising the set of storage cells.
 16. The apparatus of claim12, wherein the adjustment module is configured to stop adjusting theread voltage threshold in response to a retry threshold being satisfied.17. The apparatus of claim 12, wherein the adjustment module isconfigured to determine whether to make an adjustment to the readvoltage threshold based on one or more risk factors associated with theadjustment, the one or more risk factors comprising one or more of anerror rate, an erase cycle count, a storage request latency, an age, anda number of previous adjustments for the one or more NAND flash storagecells.
 18. An apparatus comprising: means for detecting an uncorrectableerror in data read from a set of non-volatile memory cells; and meansfor iteratively adjusting one or more read voltage thresholds for theset of memory cells and re-reading the data from the set of memory cellsuntil the uncorrectable error in the data is correctable.
 19. Theapparatus of claim 18, further comprising means for determining aninitial value for the one or more read voltage thresholds based on oneor more media characteristics for the set of memory cells, the initialvalue being iteratively adjusted.
 20. The apparatus of claim 18, whereinthe data read from the set of non-volatile memory cells comprises asubset of data stored by the set of non-volatile memory cells and theone or more read voltage thresholds are adjusted based on the subset ofdata.